Why I stopped playing, and what's strongly different since S2 and earlier.
Hey. I'm going to keep this short, since other people have explained a lot of these concepts better than I have. This isn't a rage "I quit" post, as you can see I haven't played habitually in quite a while now. I'm here to help quantify what many other people might be feeling, and perhaps bring them some level of understanding of their own feelings.
Individual momentum is what used to make league fun for me. It didn't matter what team you got or who was having a bad day. Starting in Season 3 and later, Riot began pushing the game toward a more objective and team oriented experience. While I understand in many contexts this is a good thing, it has completely destroyed my subjective enjoyment of the game. I like to go into video games knowing that my results are going to be completely and totally reflective of my own efforts. League just doesn't offer that any more.
What League offers now is a shadow of that former experience, with most of it being replaced by social skills and strategy memorization. It isn't hard to see why this is a totally different experience, and as such, that is why I no longer have any interest.