When there's a bad player on your team, your odds of winning just lowered.
When you go full cyka blyat on the bad player or the rest of the team, then you just decreased the mood, morale and odds for your team even fucking more. Good job.
When one player on your team is playing bad, then you can still win. You just need the rest of your team to play good, and the enemy team to play slighty worse than your team. When you become toxic then you destroy the mood, and the rest of your team won't play optimal. At best they will just play ok, at worst they will also start not doing very good, and then it's gg you lose.
With a bad player you can still win. A bad player + toxic player and you're pretty much just gonna lose.
It's not about some morality of "being nice to each other". It's about winning. And if you're actually in it to win it, then stop being a raging whiner. You can start raging if you want, but if you do then please stop pretending that you're actually playing to win, 'cause that's not how you win.