Sure, inters and trolls can be annoying, but honestly, what does going rampage in chat solve?
Will it make them stop throwing/inting/feeding?
Will they have a sudden realization that what they are doing is wrong because you said so?
Come on now.
Every time someone feeds, do your ABSOLUTE best to try and win instead of wasting time and energy chatting, because at the end of the day you are the one getting punished (assuming you flame)
As to the "garbage system" sure, it might take longer for people to be punished for feeding, but it does happen eventually, this is because it is harder to detect (requires manual review, and if you are aware of how many league games that get started every second, you know it's not an easy task)
You also seem to think that flaming in chat once gets you permabanned instantly, which is not the case
It might look like you get punished for flaming easier, but that is because there is a system in place to make punishments based on certain words and phrases
you CAN get an instant 14 day suspension in case you say something really bad in chat, and that is completely justified
but it usually goes like this:
10 Chat Res>25 Chat res>14 day suspension>Permanent suspension
And it takes at least 1 month of continuous toxic behavior to climb to a perma.
All in all, don't let people control you emotions and make lash out in chat, you lose by doing so, and the trolls get what they want.