Bryon,
While that is true out in your area, there are plenty of places out here where Center handles the low airspace because there are no nearby TRACONs, while heading East from here there are TRACONs everywhere. It's a pretty stark difference - If I head East around the south end of the lake, I'll hit Madison, Rockford, Chicago, South Bend, Fort Wayne, Toledo, Mansfield, Cleveland, Akron, Youngstown, Pittsburgh, Harrisburg, Allentown, and Philadelphia Approaches on the way to Wings, and rarely talk to Center. If I head due west at 4000 feet, Madison will hand me off to Chicago Center, they'll hand me to Minneapolis Center, and I think the next Approach I'd be talking to is Sioux Falls, SD.
Another example: In Wisconsin we have three TRACONs: Madison, Milwaukee, and Green Bay. We do have chunks of airspace belonging to Minneapolis and Chicago TRACONs as well.
We have 10 towered airports aside from the primary Class C's mentioned above. MKE approach handles OSH, ENW, MWC, and UES. GRB approach handles ATW. RFD Approach handles JVL. However, the other four are the ones that this scenario would apply to: CWA, EAU, and LSE are all handled by Minneapolis Center. CMY is a bit of a special case - Volk Approach (military) takes care of them when they're open, but that is a fairly limited amount of time. Chicago Center takes care of them the rest of the time.
So, in those cases, Center would be required to handle class D transitions.
JVL, ENW, UES, MWC, OSH, ATW, CWA, EAU, LSE, CMY