Funnily enough Zune wasn't even PlaysForSure. Microsoft actually killed their own music player ecosystem to try and create another one that they owned completely. Then the music industry said "fuck it, we're going DRM-free" if only so that they could sell songs outside of iTunes and have them work on iPods.

It helps that Jobs himself hated DRM on music so much that he was willing to give up a legitimate competitive advantage to improve the customer experience.