Please stop using the term "skill" when you're stating facts because you're using it wrong. There's absolutely nothing in Dota 2 that requires more skill (
by skill we generally mean mechanical ability, reflexes etc.) than Lol. I think what you mean is "knowledge", as in Dota 2 has more items and stuff to learn and therefore it takes longer to know how to play the game, in which case it's 100% true. It has nothing to do with skill though.
In terms of pure skill, Lol >>> Dota 2. There just aren't champions like Zed, Azir, Cassiopeia or Draven in Dota. And please don't quote champions that get more units to control, that has nothing to do with mechanical skill but unit management, which is an RTS thing. League is constantly evolving from the RTS mod that was/is Dota.
They can keep all of their item complexity and multiple unit management, I'll take this: