I don't actually think this is true. I think the issue is that the CLI is a much better paradigm if you're going to operate with text and text based commands.

LLMs excel at text, text is incredibly powerful in a cli environment.

It's not just that there's no GUI alternative, it's that the GUI itself is a bad affordance.

The only GUIs that even sort of successfully play in this space solve it by having a GUI that basically just embeds a CLI (see - all the vscode editors, antigravity, etc..).