It is actually way more complex than that. Nowadays it doesn't get explained a lot anymore. Especially with every system coming with some fancy bash or zsh with somewhat sane defaults.
But in the past you may have got just some naked Bourne Shell with no defaults at all.
UNIX Power Tools defined, and largely proved the sole occupant, of a class of technical literature.
It's the single book that more than any had me finally grok Unix. I still have my copy, first edition, two-colour printing (blue for "hyperlinks" to related sections).
Jerry Peek is also an absolute treasure for Unix shell wisdom --- bash in particular though he's highly knowledgeable about others as well.
This enlightens me as to how people can code with ed (and why Ken Thompson famously said 'I don't want to see the state of the file when I'm editing.'). It's basically a REPL for writing code. Same as psql, the commands you use to view the state of the text (database) are different from the commands you use to edit the state of the text (database).
Still sucks though. Even in psql I regularly drop into vim with \e to edit whole queries before sending them out.
That's a neat way to think of it. Coming from the other direction, for emacs users, using the command line is like using the editor since the gnu readline lib offers keyboard navigation like emacs.
Except ^W performs a completely different action. I can't count the number of times after switching from a terminal to Emacs within a couple of seconds, my muscle memory still not updated, I hit ^W only to discover I've just deleted 3/4 of the file.
