Of course, things have changed but people called Eurythmics (after the synth-pop era) rock or Genesis or Sting or other guys like that. Anyway, songs like "Let's go crazy" or "U got the look" or the pompous shit that finish "Around the world in a day" or "Purple Rain" or "I would never take the place of your man" or "Play in the sunshine" etc. is stuff that's clearly not R&B IMO and fall much closer to rock in an 80's sense and it's also based on songs like that I dismiss Prince as a rocker.

As for Dave Grohl, I'm sure he's a big Prince-fan but I doubt he thinks Prince made great ROCK, I may be wrong though. As a *musician*, how can you not admire Prince, you know?