Not all your personal info. But there is sensitive information hidden in those files. I don't know how much relevance DRM is still anymore, as Apple already decided to drop it last year. They are still using digital watermarking though...
Also, what's not been mentioned yet in this discussion if the fact that copyright rights usually come to an end after a certain period. But DRM-protected files means you can't share your files with the public domain, unless you want to risk the obvious privacy issues.