The "killer feature" for me about CLI is related to why I love Emacs, even though there are editors with better integrated support for e.g. Python and Java. That feature is scriptability (aka macros).

When I have a file in one format and I want to make it into another, I can record myself doing it once and I have faith that Emacs will faithfully do the same thing to the rest of the file.

Apple keeps making pushes in this direction with Applescript recording, and Automator, but they haven't succeeded yet, and I think it is because the problem is hard to solve in a GUI. Or tackled as an afterthought.

Similarly, for a CLI: you can set a script up to do what you want to one file, and then say "now do it for every file that meets these criteria." A more GUI-oriented way to do it might be to do a find and select in the GUI, and somehow apply your process to those files. But I have not yet been shown a GUI that makes this process easier than doing it at the command line.

The OP is right in a sense: you can pick a single task and show that it might be faster to do in a GUI. And the OP has a great point when it comes to discoverability. I would love a GUI that also supports the kind of hardcore every action is scriptable that Emacs does.

Perhaps such an IDE and/or editor exists, but I am too busy reading opinion posts on HN to find it!