Actually it's not, it's about the same. The difference is that a lot of sub-par gameplay/behavior is tolerated in PVE because it's faceroll content outside of endgame raiding with static groups. NIN just auto-attacking and throwing daggers while running around in expert? You suck it up and just carry them, wishing they would be forever stuck with players of their caliber and never be able to complete anything.
In PVP, players just don't roll over and die if you actually try, and part of trying in PVP is communicating with your team or knowing how to play your class well enough (in PVP, specifically) to not draw negative attention. If you're bad at PVP, you get called on it because the rest of your group actually needs you to perform to win. That doesn't mean the person is insulting you without constructive criticism, they're bringing up your shortcomings so you can fix them. That's not being toxic, it's a competition and they're trying to help you so, as a team, you can win. Have I been called out for having less than 10k HP in Feast by my healer? Yes, absolutely. It's fine at lower levels of play, but having the staying power of a wet paper bag won't fly when you're focused repeatedly. So, I accepted the criticism from the top 10 player, and was able to put myself in the top 100. Can I specifically say that his advise made me win? No, but it undoubtedly made it easier for anyone healing me.
You learn these things from people who are kind enough to bark something at you before/during/after a match. There isnt a lot of time to prepare a flowery, gentle reply to someone's shortcomings, it's short and to the point. A lot of people are deeply upset by this criticism, then cry "TOXIC" and bash the game mode.
I'd go as far to say that pro-chat ban players are the most toxic to the game--so vocal about their hurt feelings that the game is altered to being less fun and less competitive/thrilling for people who enjoy any particular content. Safe spaces are created for like-minded people, not forced upon everyone. That's the problem with the chat ban.