Yes, this looks like DNT all over again. Just another header that quickly becomes meaningless, wasting terabytes of bandwidth all over the world for no good reason.
DNT does nothing technically, but it has political power and that's where privacy happens to a great degree. When 70% of users say 'do not track me', it is hard to claim that they don't care about privacy.
It was meaningless from the beginning: DNT was always nothing but an Evil Bit. You’re getting mad at Microsoft for pointing out that the emperor had no clothes.
Is it? The whole point to this thread is that none of the big players stood by their "promises" for longer than a few months. Especially Google's hypocrisy of promoting DNT in Chrome and knowing full well their adtech teams would ignore it as soon as they had an excuse. (Microsoft and Mozilla enabling it by default sure was a "good" excuse, despite that obviously being the best interest of the users.)
It's possible they were looking for an excuse and lying. But enabling it by default definitely seemed to defeat the entire point of the fragile agreement. It doesn't matter to them whether it's better for users.