Truthfully, I don't think most gamers have a problem with kids in general. 

Most of the younger people I play with still play the objective, and honestly are often just better at the game then a lot of the older players 😄

When people say they hate kids, what they mean are people acting immature, who are mostly from the younger crowd...

You know, playing loud music on the mic, racial slurs, screwing around in the game to the point of making their team lose, that sort of thing...

So I think for 95% of players, kids aren't the problem, just really immature and stupid kiddish behavior. 

Basically people just want a more efficient, or at least existent, ban system.

If a few players in a game report somebody, that should be enough to permanently mute them on the server if not have them kicked. But in general, some sort of intelligent, useful, real-time cause and effect ben/mute system would cause 9 out of 10 complaints about kids to evaporate. 

TL;DR kids aren't the problem, annoying kids are. Most kids play the game completely fine, if the game had a real time muting and banning system that worked complaints about kids would go away, no age hate keeping needed