I disagree with you, but I’m tired of arguing about it and I honestly don’t care what WotC or s as Niobe else calls it. All I know is we used playtest characters right with PHB characters and it worked great. So if that continues I’m happy.But it matches the history of 4th Edition, which (I think) is what WotC's worried is going to happen, and wants to avoid.
In Shannon Appelcline's product history for Player Essentials: Heroes of the Fallen Lands (affiliate link), he says:
I'm of the opinion that WotC is very much aware of what happened with 4Essentials in this regard, and wants very badly to avoid it happening again with One D&D. But in that regard, they seem to be creating a self-fulfilling prophecy; from what I can tell, people see a difference between a re-release of the Core Rulebooks and simply reprinting them with some errata applied, and that the former is viewed as being at least a "half-edition" update (that is, a ".5" edition change), whereas the latter isn't.
Now, we can debate where the difference lies between applying errata and a half-edition update, but I think that's the wrong conversation, because the difference isn't seen in a critical analysis of the new books' contents so much as it is in how WotC treats it prior to release. Which is to say, you don't actively market a reprint, even if it has errata; you do actively market a new product, and when the new product is the Core Rules, then it's a new edition, either in whole or point-five.
For WotC to then openly tell us otherwise smacks of being counterintuitive, which makes people skeptical; when there's a (perceived) mismatch between your actions and your claims, you're going to start receiving pushback.