Windows and macOS actually.
Too often I meet up with people who have been using macOS for many years, ask me some simple questions, I open the Terminal app on their machines, and they look like "I've never seen anything like this before".
Windows is about the same thing, except my knowledge to CMD commands compared to Bash or SH is rather limited (the CMD is very limited in what it can do any way).
No such thing among most Linux users, maybe that's because we're just used to using it?
Each time a Linux user asks for help online, regardless of their computer knowledge, gets most likely asked to do stuff in the command line (I'll call it "CLI" from here on).
This is because unlike the GUI way, which can differ in millions of ways, the CLI way can differ only in a few ways (mostly with package managers).
And providing support in CLI at the same time teaches newcomers the importance of working with the CLI, regardless of the Linux distro, BSD distro, macOS version, or even Windows version.