[nequo]

But the abstraction that is the text editor is shared across many programs. You can use your favorite text editor to edit any of the plain-text configs that you need. Firefox’s about: and the way to edit it are specific to Firefox.

[Quekid5]

Well, yes, but we were imagining a world with a sort of universal "about:", I think?

You wouldn't even need that many basic types to cover about 90%+ of the state space. Of course, there would be bonus points if applications could define their own types in a UI-meaningful way.