Well, I am truly dumbfounded. I am new to Frontier Airlines and have enjoyed flying with them the handful of times I have flown. When I have heard the complaints about customer service and the fact it is considered America's worst airline, I took it with a grain of salt. I am beginning to think I might be wrong. This was the response I got in what I guess was the final email I received from the 'reservation specialist' that I have been dealing with:

Thank you for contacting the MyFrontier Department.

Following up on your request, let me inform you that the fact that these cities do not accrue miles is handled as internal information and cannot be shared with our passengers.
As it is internal information let me inform you again that this flight segment does not accrue miles so unfortunately you can not be credited.
Thank you for choosing Frontier Airlines.

What kind of statement is that? To her credit, she has always responded in a timely manner, but all I wanted was a definitive explanation. Wow!