No, not a metric of listeners. Just a metric of which station for a given market converts played music into purchases. I think if Microsoft shows stations the purchase conversion info, it will cause them to put more emphasis on RDS for other stations under their ownership. Stations get nothing out of it really other than incentive to play music that people are more likely to listen to and then buy.
If I'm station KXYZ and Microsoft tells me that I'm having a lot of people buy song X that I play, then I am going to play more of songs that are like song X, which means more people are going to listen to my radio for other songs like song X. it is indirect marketing, but I think it will benefit stations to know this info.