The answer to your question is thoroughly explained on the BLI/PCM website.
You and they are not paying an outside company for the motor control, and they developed the sound in-house.
Mechanical Department "No no that's fine shove that 20 pound set all around the yard... those shoes aren't hell and a half to change..."
The Missabe Road: Safety First
The Blue Line locomotives have no motor control decoder but are "DCC ready." The sound system that is in them was developed in house, so they are no longer paying a royalty to QSI. That is explained in detail in their advertising supplement to the June 2007 issue of Model Railroader on pages 59-64.