Once, League had fun players to play with. Here's my analysis on why those players are gone.
I've played League since season 1. It was a fun game. Over the next couple years, I tried other, similar games, but left them for the simple reason that Riot was doing a vastly superior job at keeping its player behavior in check. Leaver Buster made sure games got played, the Tribunal cut down the most obvious offenders quickly, pre-game player behavior messages were effective, and the old honor system was great positive reinforcement when it was being supported. Riot proudly gave a lecture on how to shape player behavior in a game such as their own - and I quite enjoyed watching the whole thing.
In the past few years, though, things have not just decayed from lack of attention, but have fallen apart as a matter of design. The game punishes players not just for playing the support position, but for playing with the support mindset. Trinkets, once a nuanced and well polished vision strategy game, are insultingly simple and haven't been improved in years. The support position itself has always been required to either be an AP mage (read: not really a support) or super-far-back-line walking potion (read: yawntown) for years now.
The most obvious error, and probably the biggest single reason for the current disaster, is that players' ability to generate in-game resources is now tied to your ability to be, yourself, the big star player. Anyone who focuses on being a team player, by taking time and risk to place wards, or to rescue someone in trouble, or to be the bait for a winning teamfight, or to walk away from a tower to give local gold to the team's hyper carry, loses any hope of getting an S rank, and therefore loses the ability to get _anything _ they didn't already have for winning. Additionally, the quantity of rewards you can get is a function of how many unique champions there are of your preferred playstyle - if you want to play a mid-lane assassin, you have more than 20 options, whereas someone who wants to be a support enchanter gets... 5 loot crates per year. In perhaps the least surprising turn of events ever, the players whose idea of a good time in League was calling good shots and taking one for the team have left in favor of games that actually reward them for doing so... myself included.
I stopped playing the game regularly when things started really crumbling at the preseason 6 update. I've checked in every few months to see if things have improved. Alas, I must report that player behavior in particular has been getting far worse each time I've come in. Now, nothing I can say or do will get the team to work together, to stop flaming each other, or to stop throwing extremely offensive insults at each other ("you're autistic" seems to have become particularly popular as of late.) The "honor" system is either used to glorify the biggest jerk on a team, or to shame someone with the "stayed cool" message while telling them they are horrible and they were why the team lost. (And, of course, doing that gives the offenders progress toward improving their own honor badge!)
Once upon a time, League was the best MOBA out there precisely because you could rest assured that when you sat down to play, you would quickly be put into a game with 9 other players who want to play, have fun, and win. I wish that were still the case, and I wish I could see any effort being made by Riot to rectify the situation, but instead I see changes that make it worse.
I'm uninstalling for now. I'll be checking news articles to see if Riot ever gets their act together again, but at this point they're playing from behind. Other MOBAs are now better at what Riot was once the best at.