No extension is necessary. There's nothing that says a website has to have exactly 1 or 0 RSS feeds and that they most be for global syndication. Anyone in control of their site can dump a plain ol' RSS (or Atom, or JSON) feed at /foo/part-3-has-been-posted.xml. I've done this on my own site.
This is not (really) a technical problem. It's a cultural one—getting people to actually make hyperspecific micro feeds available.
Nah an RSS feed has the ability to contain n feed items. This proposed new protocol would have a maximum of 1 item. The closed contract (1 notification only, ever) makes sure that it doesn't become yet another avenue for producers to push content that you didn't ask for.
"RSS but for just 1 item" and "A brand new protocol that is functionally equivalent to RSS for just 1 item" are both just contracts. What makes you think that the latter is more enforceable?
I need to point out a subtlety that is might or might not be intended in that comic: it's bystanders, or consumers of the 14 standards, trying to fix it.
Unicode was invented by Xerox and Apple employees. USB-C was developed "by Intel, HP Inc., Microsoft, and the USB Implementers Forum."
To be clear, it's not about the huge companies, it's about the people doing the heavy implementation work. They can change 14 standards into 1. And in most cases - with rare exceptions - only they can do that.