I think that's just the hardcore raiding crowd everywhere. I've seen it across multiple MMOs. When you're that highly invested in something, any changes are going to get under your skin. Especially so if competition for seats is involved.

What I wish was more universal was the dungeon etiquette. It's been a few years since I was in World of Warcraft, but the pick-up group dungeon experience there had the most toxic people I've ever seen in gaming by a long way. And I've solo queued in League of Legends!