The other difference is that chess is a 1v1 game: the only person you can blame if you lose is yourself.

Counterstrike is a team game, where (if the matchmaker was competetently designed) on average you shouldn't be able to carry your team. I think this contributes to a lot of toxicity, because it's very easy to find a cause for the loss that isn't your own skill.

Imagine a team match of chess where everyone controls a couple pieces. At low brackets, you could know "tech" like en passant or underpromotion. You might have vague ideas like "control the center" and might know a few lines of theory. You might be screaming at the screen when a teammate castles into mate-in-3 and blame them for your loss - even though you were the one who moved a pawn to h3 on turn 1.