A minor note about things like keep-lines: you can do the same thing, with more power by invoking the shell: (keep-lines "abc") is equivalent (or at least mostly so) to
C-u M-| grep abc
Clearly you can replace the grep with whatever. I do this all the time, so I have C-u M-| remapped to C-M-|.
You can do it with evil-mode (or vim) too: :%v/pattern/d runs ‘d’ on all lines which do not match the pattern. (The opposite is :%g/pattern/d.) I believe it works with any command, though I’ve only ever used it with ‘d’.
%v/pattern/d can also be written as %g!/pattern/d
On the note of TRAMP. One nice use case is to analyze a large dataset in a remote location and see the result figures on an org-mode buffer in your local emacs instance.