I guess I am getting old (still). I've always thought of commuting in its original form: regularly undertaken intercity travel. In that sense, those who live and work in the same city (and I've always counted cities that have no buffer between them as a single city) don't commute. I suppose my view is going to be unpopular here, since a lot of folks who consider themselves bike commuters are doing intracity travel. I'm not really rabid about it, it's just my opinion. It's probably different for folks who live in larger cities.
I have noticed both for myself and many carfree friends over the years that when we commute (intercity) by bike we don't carry nearly as much "famine protection" as when we are living and working in the same city. Those extra miles, usually under some time pressure, really make a difference for some of us.