Consider this a tinfoil hat theory buuuuuuut...
Months ago Riot said they wanted League to be around forever. Which is laughable. The longest lasting SINGLE game we have right now is CS:GO with DOTA2 coming in second place. Both, at most, have been around for nearly two decades. Riot saying League will be around for 50 is the equivalent to pointing at the moon and saying you're going for a home run.
However, Riot realized they now have an IP to the scale of Warcraft or Starcraft. People know this game and lvoe it, even if they don't enjoy the gameplay. In doubling down on lore, they're building the world for the eventual "death" of League that happens when they have to move on. However, this means that the IP will still exist and that they can continue making league products. After all, a lot of people dislike the MOBA genre.