Something
vvalkyri said last night reminded me of the
"What makes it dating?" question: Baggage. That nicely sums up what I was trying to say. If we are dating then I can reasonably expect you to deal with my baggage, and vice versa. If those aren't reasonable expectations, then we're not dating. This is a necessary but not sufficient condition; I have some just-friends who do deal with my shit, but no partners who don't.
This is probably a better way to express what I was saying about commitment. If you quit when the going gets tough, it's not dating.