Speaking of RSS, let me tell you the story of Drupal's Aggregator module. I actually don't know the full story of it, just my (extensive) experience with it.
I first encountered Drupal in 2004 when I met Boris Mann (yes, that Boris Mann) and over breakfast at a diner in Vancouver, he said to me "Richard, I want you to know as much about Drupal as you know about Movable Type." I fell in love right away, though this was the era when you had to import MySQL files to install a module. The Aggregator module came with the core of the software, so no database installation needed.
What's the Aggregator module? Well, it takes RSS feeds, pulls them on the schedule you define, and republishes them on your Drupal site. You can see it in action here: https://richard.eriksson.ca/blogosphere We (Boris, Roland and I) ran a site called Urban Vancouver, and every time we encountered a Vancouver-based blog, we aggregated (technically syndicated) it on the site. It got us into trouble every now and then, and we had arguments with copyright holders as to whether they were right about violation (they were) but also whether they benefited from being syndicated (they did). So we asked for forgiveness rather than permission and with experience comes maturity, so I don't know how I'd handle it content syndication (re-publication, not just feed aggregation for personal reading) via RSS would go over today.
But you know what was interesting about the aggregator module? You could categorize feeds. Correction, you can categorize feeds. The "Richard's Blogosphere" link above is a category of feeds that I just give a URL to. And get this: It comes with OPML: https://richard.eriksson.ca/blogosphere/opml so if I were to add a feed to it via the UI, it would get added there. If you were to subscribe to that OPML feed in a "Reading List"-compatible reader, the list of feeds would update as well.
Back in the 2000s (the decade), we had this idea of becoming content DJs, where we would aggregate (pull in) content via RSS, and tag each content item with a category, and it would link to the original URL. Content DJs could take that feed and further "remix" it.
That's an idea that's not dead, by the way. https://justagwailo.com/shared (which has a feed at https://justagwailo.com/shared/feed ), in its heyday, would pull in my "Likes" from around the web. Peter Rukavina (yes, that Peter Rukavina) does something extremely similar at https://ruk.ca/favourites (with an RSS feed!). Drupal is part of the mix there as well, but from what I can tell, it's a smaller part of the mix than my implementation.
Aggregator is now a contributed module, not part of core, as the Drupal core project has both expanded and simplified. I love it so much that I ported it to the fork of Drupal 7, Backdrop, and maintain it.