Aye.Funnily enough as toxic as they may act they are way worse in other game communities.
In Dota 2 for example i see so much hate mongering from American towards anybody Spanish.Telling them to get off 'Their servers' Blame them speaking Spanish for losing the game etc.
And in left4dead 2 you get 11k hours American players(I dont know how they have this many hours lol) who come on only to pub stomp new players and if you miss with infected or enemy kills your infected before you get an attack out the result is 3 americans shouting and screaming down the mic at you for 5 mins followed by a votekick.And no they arent kids.They are adults.
The reason why Us gamers act so toxic is because they take games way too seriously.Like its a matter of life and death.
Dont get me wrong there are plenty of US gamers who are nice and i get along with but a lot of them just need to relax and chill when it comes to gaming.