I won't report you for flaming because you hurt someone else's feelings, I really don't care about that.
I won't report you for flaming because I think your ky_s_ wil actually do anything harmful, because it's only words on the Internet.
I won't report you for flaming because I'm bothered by it, because I'm not and if I were I would mute you.
I will however report you for flaming, because you're being a dic_k_, and I don't like people who are dic_ks_.
Move league to a different setting, let's say a board game night with friends. If one of them is consistently being a dic_k_, I wouldn't invite him over next time, because he's annoying and I wouldn't want to play with him.
If you're having a temper tantrum and acting like that, you're more focused being a keyboard warrior than playing the game, which impacts your skill.
I'm not bothered by it, but my team might be bothered and influenced by your flaming, so you're also dragging the team down.
I wouldn't want you in my next games, because you lower my chances of winning. It's not that I'm bothered by what you say.
So the argument of "SJW LEFTIST GONE RAMPANT" is actually bullshit.
The people who report you are probably not offended by you calling them a %%%t, or that you're telling them to commit suicide, it's just that they wouldn't want to play more games with you or people like you.