The point is that AC Unity had very serious problems, which would have no doubt been fixed pre-launch in a pre-patch world. Also, if testing is as thorough as you claim, and you actually do have to have a fairly playable game to relase without obvious, terrible, bugs (Unity was unplayable for some on launch, and it was difficult to play for many others because of just how buggy it was), than Unity should have never seen the light of day.
