How is that solved on the decentralized platforms? How does discoverability work, what assumptions does it make, and can it be "gamed"?
The technical aspect of this is a mostly solved problem (YouTube and other distributors do it) but getting past the privacy aspects will be challenging - the type of person to use a distributed platform will also likely be using it to avoid this sort of tracking. Or they're in a country that has GDPR-like laws.
For any type of media, whether it's songs/bands on a music streaming service, video content on youtube, or even complementary goods in an online store, a good recommender system can and will suggest things that I would never have thought of (because I didn't know it existed) and thus could never have found with any search or tagging system.
How do I search for a song that's similar to those that I listened just now (and genre tags don't really work, they're far too broad, subjective and inaccurate) and that's explicitly not one of the songs which I remembered and just heard already?