These people aren't roleplaying, it's always about gnomes, and while I don't always think they're doing anything except participating in a fairly common trope that's existed in WoW communities for probably a couple decades it's also regularly used as code for their actual prejudice against Jewish people.

And it's hard to call them out because so much of it is already in the text, they can always claim they're just playing along. I remember a couple of Blood Elf /jokes:

"We're allies with the Tauren? Fantastic! We'll be having steak twice a week."

"So I was in the Undercity the other day and this Forsaken woman asks me if I want a facial. I said, 'You don't have a lower jaw, and you want to give me a facial?' HAHAHAHAHAHAHA!"