there is such thing as a bad advanced technique that hurts the game, but a lot of players who think ATs are bad are being extremely arbitrary. if you don't want to use them because they're hard to pull off, then don't...? and if you don't want to use a technique because you think it's lame or hurts the pace of the game (like planking in brawl) then don't...? nobody is forcing them upon you. if you were invested enough in the competitive scene to go to a tournament you'd probably want to use every AT at your disposal and have the will to put effort into practicing them. there does not need to be a middle ground for technical and untechnical games. the more techniques there are in a game, the higher the skill ceiling, and if you disagree with using them, then you don't have to...
and if you think an AT is cheap, so what? if you think airdodging out of a combo in smash 4 is unfair or waveshining in melee is too effective, there's nothing stopping you from learning and doing it too. wishing that they'd be removed from the game is an unhealthy mentality; the ARE fair. you CAN do them too. and if you don't want to sink time and effort into learning them, you don't have to. there's always other games (which is what you were trying to say, i think)
but actively wishing ATs were not in splatoon because you don't want to learn them is just a really unhealthy mentality to have. there's nothing in the way of you improving.
this is a really good article that goes in depth to the competitive and scrub mentality and using techniques to your disposal. i really suggest you read it, it words everything better than i can.