MP3 or video files should have been left pure and untouched, with their original checksums. These media files should have then been wrapped in a standardized binary container that pointed to the inner file as well as a metadata payload.
Changing metadata shouldn't change the inner file or its checksum, which would make many tasks easy: distinguishing amongst various recordings and transcodings, consolidating metadata, stripping metadata, updating album art, etc.
The storing stars (ratings), tags, etc. could be easily accomplished in a portable way without sharing them to other users.
I'm not quite sure in what way that would really be different from today. "Container files" aren't a native file system concept, so arbitrary software that doesn't specifically handle media files (like programs for backing up, file sycing, file sharing, …) still couldn't distinguish between changes to the metadata and changes to the actual media content.
(Even something as ubiquitous as ZIP-files as a sort of unofficial generic container format is still mostly treated as an opaque blob by that kind of software.)
And as for software that does specifically handle media files: What do you think things like MP4 or OGG are? Exactly, container file formats holding the raw media data. And even without a proper container format like in MP3s (the ID3 tag is just directly prepended/appended to the raw MPEG stream) it's not too difficult, and any music player already needs to be able to skip the tag data.
So nobody's stopping you from writing a fingerprinting program that only looks at the audio streams within a file, and I'm sure something like that actually already exists.
MP3 or video files should have been left pure and untouched, with their original checksums. These media files should have then been wrapped in a standardized binary container that pointed to the inner file as well as a metadata payload.
Changing metadata shouldn't change the inner file or its checksum, which would make many tasks easy: distinguishing amongst various recordings and transcodings, consolidating metadata, stripping metadata, updating album art, etc.
The storing stars (ratings), tags, etc. could be easily accomplished in a portable way without sharing them to other users.