Look, maybe you've been lucky in gaming, I don't know. I'd be interested in knowing what games you've played during that time?
But from personal experience I can honestly say it's been a problem for as long as I can remember going online. Mostly it's kids getting frustrated when playing games and looking to lash out, so they head for the worst, most offensive stuff they can come up with. They don't necessarily mean/think about what they're saying, but they want a way to get back at the person/people who are beating them. Back in the day on call of duty it was something I heard weekly, it wasn't a case of me gaming with dickheads (although yes, I have in the past) it was random strangers in the public lobby screaming the n word.
Again, mostly kids. I also received loads of messages telling me to get cancer, die of AIDS, the whole shabang. Edgelords didn't arrive with pewdiepie, has he capitalised on that market? Yeah, sure. He's regularly showed that he's anti-pc and most of the creators he associates himself with are of that persuasion as well, creators who push social boundaries of what is acceptable and are in to edgy/dark humour. Again, people don't like this when I say it, but pewdiepie is far from the 'edgiest' of the big creators, there are channels which regularly get 4m views + which use the n word about as liberally as it gets.
But anyway yeah, on certain games the use of the n word is definitely pretty commonplace. Particularly Russian or American teenagers seem to be the worst for it, shit even back when I used to play TLOU online (a pretty chilled shooter, which generally attracted an older audience) there were always racist dudes around. It's not an attempt to apologise for him, him saying it during an outburst was reprehensible and rightfully criticised, but it's a sad fact that it's a not uncommon word to hear during online gaming.
I think rightfully he got a ton of stick for what he did, a lot of creators criticised him (even ones close to him) and he was forced to apologise and lost a lot of revenue from sponsors. My personal view (and I understand that other people have different boundaries) is that a lot of the controversy surrounding him is overblown, but that particular incident was unjustifiable, there was no attempt at humour there, just idiocy. But he clearly stated to the world it was wrong and that he was stupid for doing it, and there's so far been no repeat of anything like it, so it's an incident that I think most people have been prepared to forgive.