Counterstrike is identical to chess, there's tiers of players. I never made it to CAL-I but I was the tier below. When playing against CAL-I tier people, we'd get stomped on.
Flipside, if I went to a pub, it's quite likely that I would stomp on everyone else. I still can do this in TF2 and tryharding.
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.
Ladder or ranking is the best overall performance indicator (given ideal conditions, no cheating).
It is a system of averages. I was a top 80 player in Age of Empires: AoK and easily beat the crap out of everything from below the top 100.
Above me, I could compete with most players on some maps on some days, top 50 would beat me in a best of five, but top 20 usually eat me under competitive conditions.
Most of them were already pro gamers back then and trained hard to maintain their ranking.
It piles up. Micro management especially. Being constantly a couple of milliseconds faster in organizing stuff and decision making is like a formula 1 driver who is 0,5 faster per lap. Worlds apart with 60 rounds to take.
Flipside, if I went to a pub, it's quite likely that I would stomp on everyone else. I still can do this in TF2 and tryharding.
You can't go by KD ratio. Your opponents matter.