I agree with you, somewhat, that PbtAs do away with situational modifiers. If we consider a clean or barebones (pure?) PbtA. But that isn’t so true anymore considering the whole family. City of Mist (mentioned) above is a PbtA that is all about situational modifiers and how to exploit them. Lots of floating numbers from all those tags. Ironsworn have a bunch of add+N among its moves and even more among the assets.
So there are PbtA that do embrace situational modifiers and introducing Scene Tags to them wouldn’t alter things that much.