yes, people tend to act in a more mature way as their post counts rises. i don't know why, but i start to realise that i take things more seriously now, and am more willing to take my time to contribute to the dicussions, after making several hundred posts on newgrounds.
this might be true in general if you have received early bans. however, i suspect that the rate will stay constant after a while. sometimes i just can't resist the temptation to make some bad posts or post in a spam thread, (which will ultimately get me banned), and it has nothing to do with the maturity level.