This is probably going to sound a bit silly, but legitimately the fact that it's installed on most Linux systems by default (and if not full blown vim, then vi - or rather, vim-tiny often). VSCode has the Remote SSH extension, but the last time I checked it automatically installed the VSCode server (?) binary on the remote system. Often times I'm administrating systems that aren't mine, and do not want to leave random bits of VSCode onto it. Even if that weren't the case, its a lot easier for me to just open a file in vim since I'm already at a shell, rather than having to open VSCode, then wait for it to initialize (though it is quick!), activate Remote SSH and connect to the server which triggers the same initialization since it has to start the server-side component.

Another probably silly sounding reason is that the keybinds are the same ones that you use in a lot of POSIX tools like man, less/more, Firefox even uses / to activate quick-find (while you're not in a text field of course) though admittedly I believe that is the only one, hell even bash itself if you use set -o vi (by default its in Emacs mode - this is actually a feature of the readline library that bash uses as far as I understand).

Though admittedly, those mostly are Linux/Remote Administration reasons and doesn't apply to everyone - but those were some of my initial motivations.