Nah, because as I alluded to yesterday, it would prejudice against other younger posters who, even if they do show sometimes some age related tendencies at times, don't act like a complete cunt.
I also oppose such a limit, but as I am 15, I might be a tad biased.
This whole debate is really only because of immature 16-year-old MorbidKid.
Joeyruss and I are 15, and we're both usually mature-ish.
Bass and Dirtracer are our age, they also don't seem to be causing any problems.
In fact, a lot of highly respected users were young when they joined. Estaurian Float was 15 when he joined in 2009, The Dead Cow just revealed he's turning 18, meaning he was 13 when he joined in 2012. There was also AngryGreatness who was 15 when he joined in 2011, but I don't know much about him or his behavior.
Not to mentions all the cunty, immature, ADULTS like Zorders.