This is very cool. I'm hoping 404media.co and aftermath.site do it -- those are two independent sites that I've subscribed to after hearing about them on the fediverse. Seems like most of 404media's writers are on Mastodon, at least.
I also like that this feature creates the ability to have a known link for an author across multiple websites. With that, you could show posts that link to any other article by the same author, regardless of which site the article was published on. So then you can see all the threads of discussion about all of the articles that particular author has written.