No, there's no SEO ring or anything like that.

The top publishers are just genuinely the sites that people click on and link to the most. There's no objective definition of "high quality content", there are just the links that people click or don't click when presented with search results.

Google puts the links people click the most at the top. And people tend to click on results from sites they recognize, because the internet is filled with a ton of crap, and publications whose names you recognize are at least usually indicative of some kind of minimal level of quality.

That's all that's going on.