This sounds true, but is it really true ? Have you tested it?
I've experienced it myself, seen it happen in others, and seen others who fail to step up stagnate instead. Pretty much anything I've offered here is experiential, not theoretical.
Can you people define personal growth? Personally, Before MBTI I thought I could define it easily.. but then realized that there were many ways to grow depending on ones view of the world(= MBTI type)... The finding of the many MBTI types kinda shook my beliefs systems. I used to think that my way of seeing things was the perfect way... and tended to judge people harshly accordingly to my standards("the objective standards"). So perhaps, we might start by stating that personal growth is a 100% subjective matter ?
I think mental health and stability are pretty uniform, actually, regardless of type. And that's what I'm talking about. It doesn't matter what type you are, you're looking for actual stability and contentment, which includes an acceptance of your actual place in the world, the fact that you are mortal and going to die some day, etc. All the aspects of being human. you look at people dying of cancer and the ones that come to terms with it, and it doesn't matter what type they are, they will still exude the same type of vibe.
Now, if you are talking about a particular person achieving their potential? Well, yes, they'll look different because they have different strengths and weaknesses. But I think the "maturity" is uniform, even if the details are different.
The problem with MBTI is that it considers without proof, that every type is equal. I find it to be a very idealistic NF like -- thus possibly divergent from truth- but since truth is relative, who cares...

-- way of seeing things and judging people. We could also question the objectivity of MBTI, since its roots are NF rotten. We should also define maturity and maturation. Which standards do we use to judge if someone is mature ? Kinda confused since there is no objectivity in there...
i've offered some basic principles above. How would you define it? I mean, why not ante up here, instead of just picking and asking questions, without providing any answers of your own?
I mean, I'm speaking from the perspective of someone older, who has dealt with immature parents when I was young (which means to me they were like kids -- absorbed in their own problems and unable to focus on the problems of others and play a parental role in the lives of their kids), and then struggling with my own crap leftover from childhood when I was trying to raise my own kids; and then watching friends and family struggling with crap and seeing who was brave enough to be honest about their own failings and who wasn't.
That's what I typically mean by "growth." Either you're honest about your own shit, or you're dishonest; and if you're dishonest, you can't make any progress. And when you're dishonest, you can't make progress and get better because you're blind to your shortcomings -- you go in circles and become absorbed in the negative spiral and never escape from it because you're flying blind. I watched my own dad basically fall into that trap for the last 40 years of his life and he never escaped.
Besides the problem of definition( which is a big problem for me since I cannot discuss of something unless I know its whole components!) of personal growth and maturation-- which I consider to be more of an N thing..(since personal growth is a construction of the mind, an abstract matters, a psychosis !)--
I think N's find it easier, naturally, to reduce it to patterns and general principles; S's understand it as well, but they tend to talk and think about it in concretes.
I wholeheartedly agree with you and your conclusion: mental growth is a subjective process that requires time( thus age factor) and willingness to change( thus implies that SJ people do not grow

!).
Meh. I think they might have some trouble if they're looking to rules and external structures to 'make them good people' -- but they're still very capable of understanding when they are unhappy/malcontent.
Thanks for your insight Jenny. I guess that's the kind of things that donot seem complicated for a 40 something person... but for me(20 something), I find it curious because it defies my initial beliefs( That's why I tend to automatically respect and defer to older or more experienced people !) .
Well, I think it's good to consider information in light of experience, but at the same time you still need to challenge it just to test it. If an older person is warped in some way or has not been courageous enough to challenge their own perceptions, then they will try to pass bad perceptions and conclusions to you.
I always believed that: young people were dumb in life matters( because of no experience of life!)and old people were necessarily wiser and more intelligent.Now I'm realizing that it's more of a mind projection fallacy than a reality, a fact. It seems that I have the same mind projection fallacy about many other things such as girls and the way they function...(same as many other guys I guess !).
Relationships and marriage does give you a lot of perspective about the other gender as well as about relationship dynamics. I did a lot of things that didn't work, which taught more in some ways than things that did work. I know I also got a lot of crap out of my system, I no longer care to fight about a lot of the dumb initial things I used to fight about it. There's some flexibility that is fostered, and how to compromise constructively, etc.
I used to think that older people acting dumb or saying inconsiderate or illogical things were doing it on purpose for some reasons I couldn't understand in childhood, I wasn't actually able to imagine they never acquired certain basics( or things I considered basic !)... Therefore I started acting like them to find out the hows and the whys of such behavioral or social quirks. I could not understand why they believed in a god( therefore I thought I was too dumb to understand what god really is !) for example, why they insisted every year for boring birthday parties, why they wanted me to go to school...etc
Well, again, there's some stuff I still think is stupid; but I think there are things that long-term seem beneficial. I also appreciate more "family building" stuff than I used to before building my own family. repeated rituals and traditions are actually useful, if you're not calcified within them and can change them when they aren't working.
The "god" thing is different, since there are so many ways to evaluate god. There are certain approaches to god I can respect even if i disagree with the conclusions, and other approaches I don't respect. it comes down, again, to honesty for me. Some who admits they are just choosing to believe because their values are comparable have a more mature outlook than someone who has to lie about things in life and the world to justify their beliefs.
I'm sometimes amazed by the unbiased-ness of kids also; they don't care about god before older people colonize their virgin minds... they don't care about social bullshit... They just follow their hearts and do what they mind to do. I admire kids because they are potentially the most objective beings out there !
Well, I think kids are also the most self-absorbed in some ways, but I agree too like you say that kids speak their minds and have the closest connection between desire and action. Kids have to learn to protect and hide themselves and filter things.
I'll just add some insights from Dabrowski as well, as you all know it, He thinks that personal growth is the product of consecutive disintegration and reintegration of worldview... So basically he thinks that positive disintegration is not possible for everybody and requires three things: innate ability(intelllect), overexcitabilities and a third magic factor lol.
http://en.wikipedia.org/wiki/Positive_Disintegration
Yeah, I don't like to be elitist by saying certain people can't grow, but I do think some people find growth easier because they possess the capacity, drive, and even NEED to grow. I agree with Dabrowski in that crap/adversity are potential growth experiences and that often we look worse by social standards before we look better. Growth is messy and painful.
Sorry these comments are not necessarily thorough in their wording, I'm actually out gaming right now (Pathfinder) and the GM yelled at me for "FaceBooking" during play. (I said, "I'm not on FaceBook!' bwa ha ha)