I was trying out racket yesterday and I couldn't figure out how to get the previous line in DrRacket. I tried all sorts of combinations and finally pursuing documentation came up with Esc-P shortcut. You can argue that this feature was first implemented in scheme before arrow keys were there but looking at it now it is different than everything else.

For me switching from Windows to OS X was easier (just use Command instead of Ctrl) than switching from "a generic editor" to emacs/vim. The point here is not that learning emacs is hard but that there are now a significant number of developers who expect standard shortcuts from the programs they use.