Do you actually use zsh? C-o and M-q and M-a and M-h and all the others are really nice, and as far as I know bash has nothing similar (correct me if I'm wrong). You don't NEED any of these niceties but they're very nice.
The comment you are responding to talks about Bash.
^A, ^K, m, a, n, space, ^Y, enter. Upon exit, ^Y.
> No way to set a command aside.
^A, ^K. Grab it again with ^Y.
(Yes, these are all readline shortcuts. If you think they’re a bit long, bind them to something shorter in your inputrc.)