Mask precision, plugin compatibility, scripts and actions, color profiles management, brush options, camera raw compatibility, liquify tool, 3D, font options... I just named a few that I use regularly.
I haven't used Photoshop in about 15 years. Gimp was never close to Photoshop
Krita on the other hand is basically everything I remember about old Photoshop. Even the keyboard shortcuts are pretty much the same. The price is quite right too.
What Adobe has done with generative AI has been really impressive though. I am going to probably have to give PS a try just to see what I am missing.
Creating a specification for minimum viable features of a raster editor able to replace Photoshop would be fantastic.
Could serve as a roadmap for alternatives and for bragging rights: "Painter2900: implements 99% of the Rasterflames Liberation Standard, and more!".