Interesting theory. The problem is that these flights are often really expensive when booked as stand-alones rather than as connections to mainline flights. Just as a data point, to take an example, the lowest price MKE-ORD round trips are more than double the price of MKE-LGA round-trips transiting through ORD. And the price goes up even more if your destination is a smaller market with less competition (e.g., MKE-ORD-SBN). At the very least it would seem that the higher fares paid by segment warriors subsidizing the cost of pax connecting to routes with greater competition.