I've never understood this argument unless you're coming at it from a sysadmin perspective. Sure if its available everywhere that helps when I'm sshing in to random systems to sysadmin stuff.
But I don't do my development by logging in to random new systems all the time. I do my development in an environment that I have set up to be productive with.
If you’re, for example, a developer working on an embedded platform which (even temporarily) has no ssh, and probably no emacs as well, tramp-mode won’t work.
I’m a hard emacser, but it’s true that vi is usually much more ubiquitously available, so it’s good to know how to use it.
Again, I'm saying that as someone who uses tramp-mode all the time, otherwise.
Maybe I'm wrong but I really don't think embedded developers do a lot of work directly on platforms that low level/limited.
You do your development on your main machine, automate deployment to your target, and debug using a gdb server or openocd.
Honestly mg or nano is more ubiquitous than vi. Any system that has vi installed will likely have nano as well.
nano is a very young editor, comparably, invented in 1999, and GPL on top of that. I'm not sure it even come out of the box with any of the BSDs (OpenBSD at least does not seem to have it).
vi was first written by Bill Joy himself in 1976, and I'm pretty sure it proliferated in many different forms over many, many different platforms.
mg, I don't know!
At one of the Lisp projects I worked on, this split was clearly visible. One of my co-workers had the dev perspective, the other had the sysadmin view. Both used Emacs and Slime, but one had it fully customized, and other had it bare-bones, and spent most of his time in raw terminal anyway.
(I, of course, am hard down on developer view. My Emacs config has no peers :)).
To that, I usually bring up tramp and say, who cares you just ssh in from emacs.