While this argument might have held weight once, I think these factors undermine it:
Emacs used to be considered 'expensive' in terms of disk/memory. These days, it really isn't.
Non-Linux unixes are less and less of a factor these days, and even most of those have some sort of packaging system where installing emacs is a quick operation, rather than a laborious download/compile/install.
Emacs itself has remote editing capabilities with Tramp, via ssh that obviates the need to fire up an editor on the target machine in some cases.
If your job involves sitting down at HPUX/Irix/AIX/whatever machines that haven't been updated since 1998, and don't allow remote access, yes, vi is probably a valuable skill. Otherwise, I think this argument is less important than it once was.
It's still valid. I haven't had to use vi in awhile but there are still a lot of OSes that don't have emacs installed by default. And every so often you'll wind up on a system where EDITOR isn't set and you'll get stuck in vi by accident.
The thing is, though, the subset of vi you have to learn to is relatively small. You need to know how to enter and leave insert mode, how to delete, and how to quit with and without saving. (For a non-vi user, the difference between knowing and not knowing those simple things is significant)
This is generally enough to edit the few configuration files you may need to touch before you install emacs (network, sources.list, sudoers, etc).
So even though the use case is small and shrinking, the amount of "vi skill" you need is pretty low as well. There's really no good excuse to avoid it.
> the subset of vi you have to learn to is relatively small. You need to know how to enter and leave insert mode, how to delete, and how to quit with and without saving. (For a non-vi user, the difference between knowing and not knowing those simple things is significant)
As a self-learner out in the wilderness, I don't know how I could have learned Linux without learning that basic Vi alongside. And that really is all you need to know.
When you're not working on a full linux distro, e.g. hacking a wifi router box or a network assisted storage box, you might not have the luxury of emacs available.
However, it's more likely that you will have some version of Vi. The one I'm thinking of is the Busybox version.
If you use a default server install of debian, ubuntu or centos, it doesn't have emacs installed. The installation media and recovery CDs don't either.
That is enough justification, especially when you're at a single user mode console on a ILO card when the machine won't boot and flames are coming out of everything. Vi is there for you and emacs SSH won't be saving you when the network is not up so you cant apt-get or yum emacs. It's also not the sort of time you want to start having to learn vi.
I know this because I've been there.
It's as important as it always was, much as pen and paper are.
I'm pretty sure that Ubuntu, Debian, and Centos come with nano preinstalled. nano isn't nearly as powerful of an editor as emacs or vi, but it's got most of the basic features you'll need when you're just trying to get the network up and running, for instance. I'm not entirely convinced that, for an emacs user, the added power of vi over nano is worth it in the corner cases where you can't use emacs through SSH, considering how difficult an editor it is to learn.
Emacs used to be considered 'expensive' in terms of disk/memory. These days, it really isn't.
Non-Linux unixes are less and less of a factor these days, and even most of those have some sort of packaging system where installing emacs is a quick operation, rather than a laborious download/compile/install.
Emacs itself has remote editing capabilities with Tramp, via ssh that obviates the need to fire up an editor on the target machine in some cases.
If your job involves sitting down at HPUX/Irix/AIX/whatever machines that haven't been updated since 1998, and don't allow remote access, yes, vi is probably a valuable skill. Otherwise, I think this argument is less important than it once was.