I am back to having 4v5 games 50% of the time in League of Legends, so I am giving it up for at least a few months. It is a roaring mix of people who never connect to the game, miss the first 5-10 minutes, AFK after one tower goes town, intentionally feed, wait at base for 200 gold, or (to take my last example) have their mothers tell them to come eat dinner 20 minutes into a game.
Whatever system discourages leaving games has no visible impact. It is tolerant, because technical problems happen. You need to accumulate some number of offenses before action will be considered, and then punishment is possible, and then it may rise as high as a temporary ban. I presume some number of time bans will eventually lead to a permaban, but my short Tribunal history shows no permabans for that, as opposed to cursing at people. In a F2P game, you can have as many accounts as you like, so the main penalty is that you need to log back on and have less IP. Basically, you can do whatever you want, and you have no skin in the game; the sort of person who might get permabanned on a level 30 account would love the chance to start a new account and smurf/troll the newer players.
I have mainly been playing ARAM because the average toxicity seems lower. The attendant lack of concern for playing the game (“eh, it’s just ARAM”) is rather upsetting. I presume I could have fewer of these people if I played high ELO ranked games on Summoner’s Rift, but I don’t feel willing to wade up the stream of toxin to get there. Also, I am far from a platinum player, so I am worried the game would suggest that I park for a few months midstream.