What the OP describes is child's play, with all the warnings about misconnecting and weather, etc.

Last week, I had to do WAS-ROC r/t for a family event. I initially thought of doing IAD-ROC-IAD roundtrip, figuring that even Express nonstops were more reliable than a connection at EWR (flying from DCA).

But I wasn't quite happy with the flight times on the nonstop, so I looked into some other options, and ended up booking DCA-CLE-ROC/ROC-IAD-LAS-ORD-BWI. Arriving/departing DCA/BWI allowed me to use Metro/MARC trains and leave my car at home. The savings in parking cost made this trip almost exactly the same price as the IAD-ROC-IAD option.

Then, CLE was dehubbed and I changed my outbound to DCA-ORD-ROC (a few more miles, and mainline). Then I had a serious delay on ORD-ROC and spent the night with ORD-area friends I hadn't seen.

On the return, I flew ROC-IAD on a junglejet, took a shower in the LH lounge, and then was CPU'ed IAD-LAS (T-48), LAS-ORD redeye (T-24), and ORD-BWI.(T-1). Not bad for a Gold, huh?

So, yes, these things are doable, and can be very lucrative, miles-wise.