I just spent 2 hours playing showdown and got nothing but the same 8 Pokemon in different orders. Why so over centralized?
Smogon OU right now is the same handful of legendaries which are for some shit reason not banned, and stuff like le bulkchomp le 4 Dark moves knight smogonbug smogonbird and fairies to fill whatever remaining final slot you don't feel like stuffing another legendary into.
Unless you're actually in the top fifty or so players on Showdown, you're probably stuck in the mid ranges, which is full of people who are shit at the game because they know what's good.
In general, player rankings go
bad players with unusual Pokémon < bad players with good Pokémon < good players with unusual Pokémon < Good players with good Pokémon
The good Pokémon are, in some ways, harder to use than a player's favourite Pokémon are. It's harder to build synergy when you're restricting yourself to a small set of Pokémon, and a lot of players just can't get good at the very high level teams.
Oh, then it'd be kind of silly to see things like Chatot get banned alongside weaker legendaries like Uxie.
I think people would complain about megas on every team instead of complaining about legendaries on every team, or just complain about people using good pokemon in general... which they already do.
I think good players who use unusual pokemon and/or unusual sets are at least on the same level as good players with "good pokemon". When the player is good, unpredictability can go a long way and playing against predictable teams that everybody already knows at least gives the player an obvious advantage even if it's a really good team.