In the Beginning Was the Command Line (1999)

One major advantage of the CLI is that instructions/fixes etc are very concise and can be easily communicated. If someone has a Linux system that needs a known fix, then it's trivial to send someone the commands to copy/paste into a terminal. However, if there's a known fix for a graphical program, then it suddenly becomes much harder to communicate - do you go for a textual instruction (e.g. click on the hamburger menu, then choose "preferences"...), or a series of screenshots along with some text?

I think your trailing question is a hypothetical but to answer:

Screenshots along with text, then use Microsoft Paint to mark up the screen shots. For example, circling the appropriate menu option in a thick red line. Sadly, I do not know how to graphically convey the double-click operation.

Its a time consuming and error prone process, best used if the buggy GUI application is abandonware. Otherwise, the new version will have the same bug or non-intuitive process but the GUI will be unrecognizable. Probably because some manager, somewhere, read too many HN articles and decided a user-facing refactor was the most important thing they could possibly do.

You raise a good point about GUIs changing over time. Obviously, CLIs can change, but that happens less often and is usually in response to a poorly thought out first attempt at providing functionality (or when additional functionality is bolted on).

Since CLIs are used in scripts/automation there's much more pressure for them not to change. Essentially, they become an API so breaking changes are a big deal. GUIs, on the other hand, are very difficult to automate so they can't be used in that way even if people wanted.

As an aside, I think a great foundation for a GUI application is a "server" API that the GUI interacts with. You can automate a lot of testing this way and you can give power users the ability to automate workflows. Web apps are already built this way, but if you're making a standalone app you even have the privilege of making a very chatty API, which makes testing even easier.