A lack of understanding of how the game works results in trolling.
This game takes place in Plat 1 - Diamond 3 mmr, not the highest but not the lowest by any means but at this rank you would expect people to have an understanding of how the game works and how people play, though this does not seem the case.
In a game I played recently my top laner played Garen vs Kled and was heavily pushed under turret at level 2 after being denied access to his wave whilst the Kled fast pushed. This put Garen under his tower with almost 2 full waves to clear before he could catch up. Garen pinged missing but because of his lack of lane pressure the Kled roamed mid and with the jungler managed to 3v2 our Mid (ziggs) and our jungle (rengar). Now, in my eyes, this is unfortunate but you can't blame the Garen massively for this. He got pushed in and was forced into this position yet the Ziggs flamed the whole team (bot lane included which is where I play) for the Kled roaming and said at 15 minutes he was going to switch accounts. The Garen explained he was pushed in and couldn't do anything to stop the roam and did try to warn them with several pings but the Ziggs just flamed and said "OPEN MID" in all chat. What happened after that was 20 minutes of the ziggs running to any other lane he could to try and leave a lane empty so we would lose before logging off the account at 22 minutes after calling us all "bad" saying we couldn't win without him. Up until this point the gold difference was only -1000 to the enemy team and was still in a situation where we could win.
I've seen this sort of blame happen a lot in games and it genuinely tilts other players in the games. Bot lane could be pushed under tower when the jungler decides to invade botside jungle and because the enemy team collapse first, the jungler flames and ruins the game, or likewise, bot could see the jungler near and engage and not see that the jungler is low or has no mana and flame the jungler for not coming. People don't seem to understand how the game works or have a simple understanding it and it ends up in people trolling.
I don't think riot will do anything, I don't think they'll ban anyone for intentionally giving up like this player did but it is a genuinely annoying situation to be in when some-one tilts over something that, for the most part, is self inflicted...
Maybe it's just me, I wonder if anyone else thinks that if players understood the game a little more they'd maybe get less tilted and have less trolls?