Is there any command-line text editor that people actually use to write in? My impression is that the only moderately popular ones are ed and sed and that people only use them to make specific edits to files they wrote the bulk of somewhere else.
As to CLI editors... I use cat all the time to make notes. Because it's straightforward. Firing up vim or emacs would trigger a mental context-switch (caused by screen redraw), while cat is a good CLI citizen --- it's the best thing to make quick notes with 0 distractions.
That's an alternative way of using it. And half the things you have in GUI mode stop working.
> Vim is a GUI too
Are you speaking about GVim? That's still really a terminal with Vim launched. You still can't have e.g. headings in documents rendered at a different font size than the rest of the content. You still have to deal with the nonsense of patched fonts to get nice-looking arrows with powerline. Sounds like TUI to me.