I have been thinking about this, but I'm a bit iffy about it. First it's much harder to control zip and rar files for content, and second is space.
Third, which I just discovered now.. I took a look at a random reshade file here, the
Blade&Soul Vibrance for Blade & Soul.
That file got 20 mb of textures that aren't used, looks like it is a renamed Fallout 4 shader with Profules/Default/Global.cfg changed, and doesn't seem to use anything that the 20mb file contains.
I don't know.. That seems rather silly, and I'm not sure encouraging this kind of thing is the best course of action.
Edit: What would be reasonable maximum file size if I added an optional file upload function?