TUIs are the best cross platform apps. They run on all the major and minor platforms in general use. GUIs cannot compete with browsers being the next closest thing. They can be integrated with the shell and also work perfectly well remotely w/o issues. TUIs are superior in many ways to GUIs and have a place in the ecosystem.

TUIs do not even run the same across terminal emulators.

It is a total joke to call something which depends on how the underlying terminal emulator interprets specific ANSI escape sequences "multi platform".