>>18367709Different anon.
If they only banned the Speed Boost Blaziken, it opens up arguments for other pokemon with specific abilities to be introduced to lower tiers. Unnerve Tyranitar, Keen Eye Xatu and all of those other pokemon will then have a valid reason to exist in lower tiers.
The entirety of the metagame, excluding NU, operates around hundreds of pokemon. Which then means there are potentially hundreds of cases where one pokemon can be in one tier with ability 1 and another tier with ability 2. This muddles the tiering system and makes a lot of things not very user friendly at all.
It can't possibly devolve into the "oh, X with certain EVs can fit into OU" because no one will take that argument seriously.