And the ability to focus on just aspects that are relevant. That simplifies the problem immensely.
I look at the current situation of UIs in Rust, every one of which is unappealing, and think I could build my own. The basic structure and paradigm is so simple! Then, I think... Unicode support. Right-to-left text display. Affordance for text readers.
All very important, but things I could ignore for myself, but not in a publicly shared library. And... ugh. Either I would have to spend years figuring that stuff out, or pull in a number of other libraries which adds layers of abstraction and complication. So I fire up Civ 6 instead.