All you've proven is that Garchomp is competitive at both the OU and Uber level of play, which is something several OU pokemon can claim, including Blissey and Metagross. Garchomp is not detrimental to the OU metagame, it's anther pokemon that is strong and needs to be considered when building a team for OU play. It still dies to Ice moves just like Salamence, and several pokes can deal with it. Steels switch into Outrage, flyers/levitators switch into Earthquake, Mamoswine can switch in on just about everything and Shard ftw.
I don't see it as being too much worse than Tyranitar with its sandstream ability and spdef boost that goes with it, or Gyarados Taunting walls while it Dragon Dances. It's not hard to counter, but you have to be able to counter it.