Same here for Dota 2.
An insufferable playerbase combined with thousands of obscure mechanics, details and interactions makes it basically impenetrable as a casual game for someone to try it out. I got 4k hours in it and too many of them were filled with negative emotions towards myself or others.
It’s unfortunately also the best competitive game ever made, both for playing and watching.
I’m not a avid league player, but as far as I know Flash has been mandatory in competitive on like 99% of champs for pretty much most of leagues existence.
Blink is just a different approach on the topic of instant movement skills.
Flash is free and has no downsides, but is rather short and has a long ass cooldown.
Blink Dagger is fairly expensive, can be disabled through player damage, gives zero stats but has long range and a reasonably short cooldown.
Both fundamentally shape their game for the better, because without them the game would be a lot slower and less spectacular. Probably 80-90% of all “greatest highlights of dota” scenes feature a blink and I presume it’s vice versa in league.