Feed URLs aren't identities; podcasts need a GUID
Quote
if Dave's amazing podcast at RSS calm, then moves over to fireside now, the Feed URL is different. And nobody knows who nobody knows is the same.
Episode 41: We are the super spreaders. I'll give you context to that (approx., from transcript intro) 00:55:58 (play audio from this timestamp, opens in a new tab)
Voice-matched
Summary
Podcasting has no universal ID, so everyone keys on the feed URL or Apple's ID. When a show moves hosts, its URL changes and nobody knows it's the same show; at worst aggregators hold duplicates. The podcast:guid tag fixes this with a UUIDv5 hash of the feed URL at the moment it's implemented, under a shared namespace, so the ID stays the same when the show moves.