Once you have mastered Emacs, you are good at all other editors
I haven't found that to be true at all. I find that due to archaic idiosyncrasies and the customization possible with emacs, the more time I spend with it the more difficult it becomes to use different editors.
I haven't found that Emacs has made it harder to use other editors. It's just made me realize how horrible it's always been to use them, hammering away at the arrow keys, using the mouse way more often than should be necessary, spending time on fixing whitespace that should be spent writing code…
Then there's the fact that Emacs really isn't an editor. If anything, it's a shell that runs elisp programs, chief among which is a text editor. Programs like magit and ansi-term (and gnus and compile and dired and TRAMP and…) are good examples of this.
That's similar to what I joke about it being when people complain about it being bloated: It's a LISP VM, which happens to have a thriving ecosystem of utilities that run on it.
Germane to the conversation that emacs make you "good at other editors" (nb: Are other editors as programmable/versatile as Emacs and vi -- certainly edtiors need to be able to rise to a level required by the operator... I haven't worked w/ textmate or sublime, etc., etc.) -- I've recently shelved Emacs for vi to "level-up" my vi skills. I'm as I delve into vi, I'm finding facilities that I really hadn't imagined in my previous episodes w/ vi, and I think part of it can be attributed to my years w/ Emacs, and the attitude that it instilled: "There has to be a way to do what I'm imagining".
I spent 5 years learning and using vi (n perhaps a dozen different Unix-like OSes, so they were all different, meaning I could only use a core set of features.
I then spent a few years working on Windows where I had Vim, but other editors I used were, well, 'standard'.
Then ViEmu came along and I now move between Vi-like editing in VS and Vim, and 'normal' editing in other apps.
It's not too bad, to be honest. I'm editing in a non-vi-like-manner in this comment box. I could probably install something to make Chrome do vi-like editing here, but my brain is happy to switch modes, if you'll forgive the pun.
There's also uzbl which is a browser that natively supports vi-like browsing http://www.uzbl.org/ but beware, there were some bugs with the TLS validation process iirc, not sure if they're fixed yet.
True I rarely have a problem editing in web text boxes, I never really committed to using emacs as a word processor. But I'd be lying if I said I've never accidentally closed a browser tab when absent-mindedly trying to do a backward-kill-word ('ctrl-w').
I was thinking more about programming and system administration. After years of using emacs, I find it harder to adapt to the popular mainstream tools like Visual Studio, TextMate, etc.
I haven't found that to be true at all. I find that due to archaic idiosyncrasies and the customization possible with emacs, the more time I spend with it the more difficult it becomes to use different editors.