Flamers

Too many people in this game are very quick to play uncooperatively, selfishly and undermine another person's game but then flame at that same person for not doing well by citing the score. For example, in one game of draft pick, the person who picked first called top and picked a top champ (malphite), then two players picked junglers and another person picked top, leaving one bot, two junglers and two top when the game started. The original top player decided to go to fill mid as a less-than-optimal champion as the other laner was being stubborn and throughout the game there was little support in the way of SS pings on the enemy jungler whereabouts to help prevent ganks, many people KS'ing from this champion and some players started flaming at malphite for not doing well as his score was low.

Malphite said had been helping deal a lot of damage in team fights, doing most of the damage to champs usually, but on most occasions someone else got the final blow, when he called someone on actually ks'ing him they said "it's a team effort", ignoring the fact that although that champion had been helping with this "team effort" on numerous other kills and still flaming him for a low kill score. Some of the team members then reported malphite for not doing well, "feeding", etc

What can you do about players like this? I see this all the time in games where people just look past how they contributed to another player doing badly and focusing on the fact that a player had a bad score. The most classic example I have is players who top with a Garen that decides to "carry". The Garen ensures that he gets the killing blow on all top lane kills, leaving the other top laner to get none and then complains at the same person for getting no kills, having poorer items, etc.

I feel that this is a huge community issue where players will just undermine one another and then flame at the ones who aren't doing as well, ignoring every single factor that could contribute to that and simply saying that they're " a bad player" or "a feeder" or whatever or accusing them of "flaming" if they try to defend themselves by arguing back.

Does anyone have any advice on how to stop this from happening to myself and other players?