If they were just trying to build an editor, sure. But they're trying to build an Emacs, so it makes sense to address a major pain-point that Emacs has: drawing

If they were just trying to build an editor, sure. But they're trying to build an Emacs, so it makes sense to address a major pain-point that Emacs has: drawing, adding to the UI, and radically changing how the contents of a buffer look is at worst hard-to-impossible and at best inflexible and hard to find documentation on. Starting with a well-understood document model that a lot of people have experience with making look however they like has a ton of benefits. You can build things like ink[1] without needing the core editor devs to forsee your need for nestable menu primitives, for instance. [1]https://atom.io/packages/ink https://atom.io/packages/ink