First I'll point out that I'm open-minded and I'll try ST seen that so many people say good things about it.
However I'm not sure that's one of the biggest issue from people coming from a vim/emacs background.
I'm using Emacs because there is more than one million line of elisp code in Emacs and all its mode and there's no way anything is going to offer anywhere near close what Emacs has to offer.
Just an example: you can search and replace on a regexp and use friggin' Lisp substitution in the replacement. Say I've got this:
foo = 1
bar = 2
... = . // 96 more lines come here
baz = 99
I'm not saying it would be good style or anything to have "code" like that, but if I want to replace it with
foo = 5
bar = 10
... = . // 96 more lines come here
baz = 495
Well.. This is trivial under Emacs. And it's not trivial because that particular use case has been thought of previously: it's trivial because search and replace can use Lisp substitution, which is wild.
There are too many to names but I'm regularly using, under Emacs: real-time validation of XML files using Relax NG, ace-jump-mode, paredit (sweeter than sweet), magit, org-mode, etc.
But, most importantly, instead of having to adapt myself to the "text editor", I can adapt the text editor to myself.
Is ST3 as extensible as Emacs?
How complicated would it be to, say, implement the equivalent of vim's easymotion / emacs' ace-jump-mode to ST3? I'm not asking if someone did it: I'm asking how "complicated" it is for one to be able to adapt his too the way he needs.
I'll try ST, to see what the fuss is about...