I mean, yea, there's ways to do it with a different workflow. (And in GIMP, I've done exactly as you describe) But the mechanism + data flow in Photoshop also let you work naturally w/o those extra steps. The mental model of placing a physical filter on top of a physical image is mapped better to PS's method. Say you want to draw on a layer under the filter? In Photoshop you can just do it, and filters above the layer will be updated properly. (I imagine in PS this mechanism permits better data/memory management) By duplicating layers, I imagine GIMP has to keep extra copies of the data around that it cannot discard, because it cannot re-compute it.

Mind you, I haven't used Photoshop in years and GIMP (or Krita) has proven well enough for the image work I need to do. This is just one thing that stuck with me from 15 years ago!

Let's say you want to stack a contrast, a saturation, and a color temp adjustment layer (or levels/curves/or a color threshold/etc.), then want to keep tweaking them until you're happy. I do this often. Or you have them right but just want to change the mask a bit to add/subtract a bit you missed. Or change the image under those adjustments. It's trivial with adjustment layers and done in a few steps trivially. It's not if you're copying layers and tweaking away and backtracking and reverting in separate layers.

Simple answer is that those bitching about lack of features want GIMP to provide exact same features as Photoshop with exact same workflow.

I wonder if these same people also bitch about learning new languages or frameworks when technology moves on.