What made people enjoy this game, and what has changed?
I've been playing some traditional grand strategy games in multiplayer lately, and had a realization about League and why it resonated with people so much that we played a ranked 5v5 game with strangers for years on end.
The draw is simple: abstraction.
League is relatively simple and low-mechanical most of the time, at least in terms of the barrier of entry. Compared to RTS, you're only managing one character at a time, and compared to turn-based, you're dealing with far fewer processes to micromanage. There IS a cost to this, but the payoff is that interesting and coordinated macro-plays can actually happen without a prohibitive amount of effort. Go play the more involved games and tell me how often those big moments actually happen; it's always just one side bulldozing the other because one of them micro'd better.
League was compelling because the game was largely determined by deliberate moves the players made, collapsing bot and intuiting everyone's movement on the minimap to line up the play. Micro mechanics existed, but they were essentially a source of power rather than how you actually took over a game. Playing the map like this is something games have a hard time offering: mechanics are too complex and nobody bothers because you can win on the back of the mechanics, mechanics are too simple then everyone learns a basic algorithm for the macro and it gets stale. For all it's other problems, league nailed this.
I don't need to explain the problems the game has now, and why they diminish this experience. Choices don't feel like they matter. Not oneshotting people feels like trolling. Risks are too high for bold macro plays. The best way to have agency is to negate everyone else's agency. High damage stifles many strategies. We've all heard this.
Riot really needs to think about what this game is supposed to offer. Smash already exists and is really good, a mechanically inferior Smash with death timers and some strategic hoops to jump through is NOT a good direction to take this game. Get back to letting us sweep around the map in a calculated but casual way, like you never really get to in RTS and 4X games.