Google.

For a while, Google gave you good boy points for including microformats, and they still offer tests and validators [0] to tell you what the crawlers get out of your page. Supposedly microformats would not just give you better SEO ranking but also help Google connect people (like the fediverse) to accounts, so that you could surface things relevant to person by searching for the person.

[0] https://developers.google.com/search/docs/appearance/structu...