— In a terminal, I can do so-and-so with a simple command
— Well, in my FrobnicatorStudio, there's a shortcut Ctrl+Alt+So for that
and this can go forever, going into pretty much useless comparisons like "in vim, I can delete 24 lines by pressing four keys" (no Sublime user ever needs that) vs "in Sublime I have multiple cursors" (no vim user ever needs that either).
The proper argument here, probably, is this one: the terminal, with its way of combining small CLI tools into pipelines, covers infinitely many use cases, but indeed has a learning curve, taking probably a year or so to become really comfortable. When you reach that point, you will be, on average, much more productive than an average GUI user, but it requires some dedication, pain, and suffering to reach that point, and people often do it involuntarily.
In my case, my first job required managing customers' servers over ssh, those servers had bare minimum installed (often vi, not vim), and I had no choice other than figuring out how to do things effectively in this setup. If not for that experience, I'm not sure I would've gone through the pain of starting doing things in the terminal.