RSS represents the antithesis of this new world: it's completely open, decentralized, and owned by nobody, just like the web itself. It allows anyone, large or small, to build something new and disrupt anyone else they'd like because nobody has to fly six salespeople out first to work out a partnership with anyone else's salespeople.
That world formed the web's foundations — without that world to build on, Google, Facebook, and Twitter couldn't exist. But they've now grown so large that everything from that web-native world is now a threat to them, and they want to shut it down. "Sunset" it. "Clean it up." "Retire" it. Get it out of the way so they can get even bigger and build even bigger proprietary barriers to anyone trying to claim their territory.
Well, fuck them, and fuck that.