Honestly I think it is pretty simple. League is a funner game in terms of actual gameplay. Less strategy sure but more than enough that the game is always varied and never gets solved. More opportunities for individual plays, constant trading etc. makes the game much more satisfying. You can't really enjoy the strategy elements until you're good enough to understand what is going on, you can quite easily enjoy the gameplay from the get go.
Dota is also really confusing for a new player imo although I imagine League is starting to get that way too with some of the changes in the last few years.