That's probably more in line with what I was trying to say in the end. I apologize for the phrasing mixup.I feel like the "it doesn't exist crowd" really only comes in when someone loves something and an adaptation or sequel is just utter garbage. The betrayal crowd for SAO probably hate the show very much, but not enough to completely deny its existence. That takes some prior attachment.
I still don't get the extreme hate though. Maybe it's just an effect of the internet and fanbases becoming even more connected and turning everything into a giant echo chamber.