> really don't get terminal UIs that try to rebuild GUI-like functionality.

Because it's easy to get things done for a TUI, but if I create a proper GUI, my codebase is suddenly more complex. And it's not like there's a solid, reliable GUI toolkit that I can use, they're all riddled with different bugs and caveats.

> Flutter's ok

If you ignore the absolute nightmare that is building applications in Flutter. Even Flutter itself isn't really designed to be compiled by anyone (although, in practice, your distro will shield you from this issue).