Where does it say that it chooses specific decks?
It literally starts off with saying that it matches by stars, or MMR:
And then goes on to explain how that works.
At no point is there any need to “counter queue” you into a specifically chosen deck to lower your winrate, as facing tougher (i.e. better performing with higher MMR) opponents will do that all on its own.
It’s all laid out right in the post that you’ve linked in here. Nowhere in that explanation is deck composition taken into account for matchmaking. You’re reading something into it that quite literally doesn’t exist. The “we want fair matches” part is right there in the same paragraph as explaining why we’re matched via star bonus at the start of each month - to prevent the noobstomping that happened like crazy for the first week or so of the old style of ladder.