Comment by kevincox
> but how much of it is RSS-as-such
Almost all of it. RSS is just a much more specific term than "feed" as many people talk about their Twitter or Facebook "feed". I have yet to see a reader that couldn't handle both RSS and Atom and you will see a mix of formats being produced.
I wrote a bit more detail about this in the past: https://kevincox.ca/2022/05/06/rss-feed-best-practices/#form...
One exceptions are sadly podcast feeds and clients. Although technically the additional podcast elements or just a basic "non-funky" podcast feed shouldn’t be a hard problem, the podcast ecosystem mostly ignored Atom and produced and parsed only RSS 2. Even Apple‘s iTunes/Podcasts.app which launched in 2005 with support for both, gave up official support for Atom some years ago.