The command line is great because it makes it easy to automate tasks involving multiple arbitrary applications. It's why we still use it even after GUIs basically became mandatory on all user-facing computers.
Yes. IOW, GUI's are not as easily scriptable as CLI programs, to compose operations from combinations of other operations, even though some tools to do stuff like that do exist, e.g. AutoHotKey and others like it.
A classic CLI command composition (a.k.a. pipeline) example:
