I dunno man, I could have sworn someone said something about it as soon as the first sentence of the linked article.

Even those people who just read the headline and start commenting could probably assume it's relevant to the conversation at hand considering the giant picture of Mark Zuckerberg at the top of the page.

"Our biggest public spaces" implies "social media" already. This comparison is hanging on the opinion that social media are the biggest public space we have, but is otherwise a reasonably correct rhetoric.