The way I approach these questions is...
I'm a lore nut. I LOVE learning the stories and about the world a game is set in. When it comes to MOBAs and FPS games... I just don't care. We play quick matches that last half an hour, with set characters and set abilities...
I care about my characters in an MMO / RPG where I can design what they look like. I can give them backstories and personalities. I need to know about the world so I know how my character interacts with it.
In a game like LoL where you enter a lobby and get a game, then leave once victory or defeat is achieved, there's no reason to become attached to any of these characters for me. I haven't even watched a single Overwatch 'lore' video, that's how little I care.
I'm just always surprised that people care so much about the lore in a game where lore doesn't really matter for gameplay.
Finally, you have to remember that Blizzard started with a game from scratch. They built it from nothing, so yeah, they were probably writing lore from the very beginning so it's cohesive.
LoL was much smaller when it started- they had the basics for a world fleshed out but as I said, it's a game based on matches, so you don't really need much because MOST people don't care about anything beyond gameplay. Now that the game is much more popular, they're rewriting EVERYTHING, and trying to make it cohesive as they go. I think that's a lot of work- and maybe they're taking too long to do it, I wouldn't actually know. I don't work for Riot and can't speak officially on it.