Which is fine if you do everything locally (because you control that configuration), but not having escape really sucks when you are on servers a lot and you can't necessarily go changing vim settings around.
I don't know why that would be anyone's preference given that if you used telnet to connect to a remote shell, ^] is the default escape character. So using ^[ to exit input mode is dangerously close to popping you out of your telnet session. Someone who claims to have used vi for 25+ years (get off my lawn, ssh didn't exist back then) would have likely used telnet and been bitten by that more than once.
I love jk, been using that one for at least 8 years. I even got in the habit of tapping it a few times while thinking, sort of like how you might sometimes shake your leg or whatever. I trained myself off of that though when I had to use Eclipse more and more -- edits or undoes to a file can bring Eclipse to its knees....
Yeah, I'm not sure I'd even call it a command - but it is pretty fundamental to vi usage, unless you're using some alternative like ^C or the "remap typing 'jk' to Esc" trick. When you're saying you've never used the Esc key, you mean you only use the Esc key to take you out of insert mode, I guess?
EDIT: Thanks for the replies, other people. I personally use ^C, I was curious what 'mozumder specifically used. :)