I think Nostr is great for discovery. The only method we have for RSS right now is a centralized database called the Podcast Index. We could use Nostr relays to decentralize that index and provide a way to share music and podcasts with friends and others.

I don't think Nostr is suited for hosting content. RSS is a simple text file that you can host on any webserver along with your MP3s. Webservers are very good at serving small static files like RSS at scale and can do 10k requests/sec out of the box. Compare that to Nostr, which can take multiple seconds to find a single piece of content spread across multiple relays.

The problem with RSS is the user interface. Many people want a simple user interface for it and don't want to learn how it actually works. We do have https://musicsideproject.com and https://sovereignfeeds.com that let you fill out a form to generate an RSS file. You still need a place to put that file and some people don't want to learn how to upload files to webservers either.

I think there's a good opportunity to combine the strengths of each technology and build something great. You could build a Nostr app that uses Nostr relays for podcast/music discovery, uses RSS to build podcast/music feeds, and uses Blossom to host the RSS feed and MP3s on a webserver for you.