I feel like the solution is to just stop playing, is that accurate? I can't get into a game where there isn't someone hardcore trolling on one team or the other. There's ALWAYS one, two, or three people intentionally ruining the game for everyone else because they aren't happy with their empty life and they actually enjoy making other people upset.
What causes this kind of mentality in so many people? If you legitimately get entertainment out of pissing someone else off, you are mentally insane. You have mental problems that are not normal. Is there any way, other than uninstalling, to deal with these people?
My suggestion is to be very harsh on punishing these kinds of people. That means a trusted person, most likely a Riot mod or someone that can volunteer that is deemed trustworthy by riot, to physically watch a replay of a game and monitor player behavior. If they are found to intentionally be creating a miserable experience for other players, they need to receive a suspension. First offense, 3 days. Second, 1 week. Third, permanent.