I'm ENTP, and I get told that I'm a bit immature and childish for my age, and that I need to grow up. I think this has to do with our inferior Si tied in with the fact that society has a traditionally accepted notion of "mature", and we don't really give a shit about that notion. What is maturity anyway? What entails acting like an adult? I've found that my own answers to these questions are highly correlated with Si and that they are a bit arbitrary anyway. I'm not sure what the point is, outside of pleasing societal expectations, something that's not high on the priority list of Ne-doms.