I said nothing in-game, mind you, because I know how riots stupid fucking system works.
Clearly, you don't know how the system works, because you can still absolutely get punished for misbehavior in the post-game lobby.
I wouldn't be surprised if riot still gives me a chat ban...
It's highly probable, all things considered.
because of their...discipline system that can't accurately see who the true bad people are.
I just spam pinged and then called him an inbred degenerate in post game.
Yes, because spam-pinging and calling people "inbred degenerates" exclusively in post-game lobby in the vainglorious hope that you can evade punishment are the hallmarks of good, sportsmanlike players. /s.
If you reported them, their behavior will be reviewed. This does not exempt you from the rules, and if you get punished, it is not due to a fault in the system, but because you broke the rules.
It's complete nonsense to be expected to calmly say nothing and "just play to win" when you're getting trolled by your laning partner, and 3 other people are flaming you for something you didnt do.
You have the mute feature - if people are flaming you, use it. Yes, it is difficult to play around a troll/intentional feeder; oftentimes nigh-on impossible, but flaming them (and consequently, giving them the very reaction they want out of you) isn't going to magically make them stop trolling or fix your situation in any way, shape, or form.
All flaming does is get you punished on top of your already shitty experience and encourage the troll to troll more. Nobody expects you to be calm; but Riot expects you to at the very least abide by the rules you agreed to.