Are we thinking of the same Valve here? Sure TF2 may have taken forever to come out, but Valve has awful QA when it comes to updates. In one update they changed how the bounding boxes worked for jumping, this made people not be able to make jumps they could before, and the engie couldn't even jump on top of his sentry. And Natascha's been broken through various means so many times it isn't funny. And you also have the new unlock system, which without a trading system breaks the whole concept of how they wanted players to get new weapons.
Don't get me wrong, I love Valve, they just need a QA department that actually knows how to test.