Xerox PARC, Atari, Amiga and many others had shells, without needing to live on a teletype world.

It is only cross platform as long as it pretends to be a VT100.

It's not about needing to live in a teletype world, it is about how language/text is just a better interface for a general use computer. Computers primary feature is that they are programmable and an interface that allows you to take advantage of that is superior to one that doesn't. The programmable GUIs all failed to gain traction (smalltalk and like), that left the shell (and maybe spreadsheets) as the best UI for this. Though as AIs mature we might see a shift here as they could provide a programmable interface that could rival shell scripting.

	▲	int_19h 6 hours ago \| parent [-]
		The reason why GUIs became so popular so quickly after they were introduced is because text is not "just a better interface for a general use computer". Like OP, I remember the days when command line was all you had, and even then we used stuff like TUI file managers to mitigate the pain of it.