What people don't understand is that if you were to take marksmen out of meta

You'd literally have to change the mechanics of the game. The reason ADC's are so good is because turning speed isn't slow and your character will move instantly to where you click without delay. That's why marksman bully any melee champion.

If Riot were to make a meta that supported bruiser bot lanes along with ranged bot lanes they'd either have to make them extremely broken (Mordekaiser), or they'd have to completely rework the mechanics of the game.