I think the problem isn't so much "underage" as it is "immature". I'm 17, and I play Call of Duty and other 18s. I've played them for years as well, I don't find it any big deal because I either never speak online or try and act like a decent human being when I do. Underage gamers can be alright, and a large portion of the time it's people who are of the age requirement who are immature, blasting music, and acting like dicks because they feel they have the right to since they're not too young to play. Eh, whenever I'm playing I usually just mute annoying people or stick entirely to party chat.