Thank you for your in-depth reply!
I learned a lot about the internal discussions which is great.
"filleting creates new vertices and the parameter wouldn’t make sense on the new vertices"
I see now. This does makes sense in GN though as that’s parametric until applied.
Yeah in my mind (coming from 2D vector software) edit mode could also be parametric. Some software (like Affinity Designer) treat the new points conceptual and not selectable until applied (similar to GN) and some (like Illustrator) keeps it procedural just until you grab any point of the newly created ones (I believe this the dumb way of doing it and would make zero sense to Blender)
What do you think about this:
I think a possible way to port this to Edit mode would be a separate parameter but the moment you use it, Blender creates a GN modifier and updates it with everything you do in edit mode. It should be that simple. (similarly to for example how a new particle sim creates the corresponding modifier) Then you can apply it and get to the new points if you want.
Ah this would be a dream scenario!
I hope for the best for every topic you mentioned