How about, "Turtles all the way down just like Emacs?"

I think you don't really have to come up with something revolutionary on top of the Emacs philosophy for it to be a very worthwhile pursuit. The things you mention plus the fact that it's as easy to get started as Sublime (or aims to) makes it a fantastic entry point for lots of new people into a tried, true and powerful way of working.

Sadly, it's not open source.