Yeah. I don't believe it was a planned thing at first. And then I guess someone changed their mind to just give everything a little bit of a boost if the developers don't get around to it.I know.
There was no mention of a "boost mode" when the PS4 Pro was first announced. Devs had to come out with a patch to take advantage of it
Maybe they were holding back out of fear of compatibility issues arising if the specs were different. Which doesn't make sense given how PCs scale, but probably just growing pains for consoles.