Earlier quoted context omitted.
Mozilla had half a billion dollars each year to work with, I am sure they could have figured something out if they cared. But hey, instead of fixing some HTML tags lets reinvent a completely new format and require every singe website on the planet to adopt that, that'll sure work out well...
A publisher does not want countless browsers scraping arbitrary web pages just to see if they’ve changed when they can instead offer a single lightweight end point specifically for content that is intended to be updated. If browsers started doing this scraping I can only imagine the arms race. I can only see this happening as a service. A company crawls the web—probably a search company. Their LLM classifies changes.…
The problem with the "single lightweight endpoint" is that it has to be maintained. RSS is literally a whole shadow site, with finicky XML validation to worry about on top. I've worked on multiple projects where the RSS endpoint was broken much of the time. It's both fragile and not very visible.
A solution involving client parsing of semantic markup at least has the benefit of requiring zero maintenance.