Because internet predators can so get you by knowing your age. OOoOooOooOoo
Seriously, predators "hang out" at places like MySpace, where kids just put all this information about themselves out on display for people. Video game message boards? Unlikely. Too obscure and too much of a "challenge." Regardless, nothing can happen just from telling someone your age.
Anyway, I'm 19.7.
Personally, I think having
birthdates is much more effective than knowing ages, since ages change; birthdates are constant. Also, it's easy enough to just check people's profiles and the calendar.