There are some really powerful UIs that are extremely flexible, like spreadsheets, or ComfyUI, or certain issue trackers. On the whole however I would say they all still are mostly their own interaction silos and integrations with other programs have to be explicitly built for each app.

The great thing about a shell is that you can glue together programs that don't know about each other. This is not a silver bullet, with shell programs being text oriented etc., but it does give rise to some powerful possibilities that don't really work with UIs.

Sure, and at some point you're limited by physics. But "limited by the universe" and "limited by what a product manager imagined in 2019" are pretty different kinds of limits

This is the exact problem with the Unix greybeards smug nature: no matter how low level you go you are always on top of some abstractions.

Criticising people just because they don't use your choice of tools is just elitism and leaves a bad taste.

If someone uses a GUI to accomplish their goals that should be complimented not criticised.