I understand what you mean, thought I wouldn't go blaming 'WoW refugees' for that. I remember being asked if I was dropped as a baby just because I mistakenly used a DoT on a Lakshmi Ex add, which killed it, ruining the run. It was a sincere mistake but someone lashed out at me for that. And that was way before the big WoW exode.
Some people may think it's silly to feel upset because "someone insulted you on a video game, get over it", but it's still real human beings insulting you, despite it being 'over a video game'. I remember wanting to cry back then, I felt awful.

Today I learned to take it on the chin and remember I probably never will come across these persons again, but still, sometimes, it hurts and it's stressful.

Now, whenever I want to do something throught PF, like clearing an EX trial, I just open a PF that sounds silly, like "Oh we all suck anyway, let's try to do this!" It might sound weird, but it tends to bring happier people and/or less salty players (in my experience at least). And if you come across someone insulting, welp, just remind yourself that at least, you're not like them and you won't see them again.

Of course, there are people getting offended over the slightess thing, but that's something else lol