It's worth noting Microformats is introduced 17 years ago, and was last updated about 12 years ago. It never really picked up traction, largely because players like Google have their own knowledge graph, and similar structured formats like RSS have lost their popularity since then.
That's not exactly accurate. The wiki has been edited recently, and change discussions are now done through github issues before updating the wiki, as that is more convenient than inline chat in many cases https://github.com/microformats
Also a lot of the practical discussion of microformats use is at the indieweb wiki - see https://indieweb.org/posts#Types_of_Posts for h-entry for example
SEO was always a good argument to adopt some of the microformats. Search engines can make use of that to pick apart content. It's just that we have a few more tools than just microformats for that now; including some structural html 5 tags.
What died out is attempts to do stuff with microformats via browser extensions. This was once a thing that e.g. MS did when they launched Edge. Those extensions have largely disappeared or just never really caught on.
