At the expense of having to either hope devs do it or only use extensions that give the source, having to do it for every extension individually, having to redo it every time you want to add or remove a URL, no longer getting automatic updates, and having to redo it every time you want to update.

I get the sentiment but it's not worth the hassle, especially when it would be trivial to have this as a browser feature that would solve all of those problems.