system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is League Of Legends & Dota, why is it so competitive to the point there are famous members, and why is it so popular?

I see the LOL sub reddit on the Reddit front page so often. My friend plays it but hasn't really explained properly why it's so popular. I always see how it has a huge audience, and huge competitions, and that some players are viewed as celebrities!
gpt
They're a type of game called a MOBA (Multiplayer online battle arena). You can google that if you want more info on the specifics of how the game works.

They're so popular because they're team based games that require a lot of teamwork and strategy to succeed at. E-sports started a while ago with general tournaments for fighting games and shooters and whatnot, but the heavy team based aspect of MOBAS really pushed them to the forefront of the E-sports world.  The games were even designed with this is mind, they have specific spectator modes where you can simply jump in and watch a game being played. The games also have an interesting learning curve, in that it's not very hard to learn how to play, but it is very hard to get significantly good at the game.

If you want to learn more check out twitch.tv League of Legends is usually the top game being streamed on there and a lot of the professional players stream their practice sessions. Watch them and you can get a feel for what the game is like at higher levels of play.