Progressive and independent journalists are raising grave concerns this week about Facebook’s plan to fashion itself as an arbiter of what news outlets should be deemed “trustworthy”—arguing that the social media giant’s new proposal will punish non-corporate news sources and journalists offering left-leaning news analysis that it finds to be “polarizing.”

Richard Kim, executive editor of The Nation magazine, was among those reacting critically to the social media giant’s announcement on Monday:

In his keynote speech at Facebook’s annual developer conference on Tuesday, CEO Mark Zuckerberg revealed that the company has already begun surveying its two billion users about the news sources they recognize and rely on the most, to determine which media outlets are “broadly trusted.” The results of the data-gathering will determine how widely news outlets are featured on user’s news feeds.

“We put [that data] into the system, and it is acting as a boost or a suppression, and we’re going to dial up the intensity of that over time,” Zuckerberg told media executives after the speech. “We feel like we have a responsibility to further [break] down polarization and find common ground.”

The CEO’s meeting with the media included representatives from some of the largest news organizations in the country, including the New York Times, BuzzFeed, Atlantic Media, CNN, and News Corp., according to the Huffington Post.

It also follows months of criticism of Facebook after the alleged spread of misinformation on the platform during the 2016 presidential campaign.

“It’s not useful if someone’s just kind of repeating the same thing and attempting to polarize or drive people to the extremes,” Zuckerberg explained to a crowd of developers regarding how the company has begun to decide which news sources are credible.

But while combating the spread of misinformation is a worthy cause, argued some critics, Zuckerberg—CEO of a powerful corporation and one of the world’s wealthiest individuals—should not use survey results to support his role as a self-styled “gatekeeper” of trustworthy and untrustworthy news sources.

As Julianne Tveten wrote at In These Times last fall, Facebook began flagging so-called “fake news” after the election, along with other major tech companies like Google, which pledged in April 2017 to “surface more authoritative pages and demote low-quality content” in its search engine results, as Facebook is now doing with its news feed.

“These adjustments, however, haven’t stifled propaganda. On the contrary, they may have stifled dissent,” Tveten wrote, noting that left-leaning news sources have seen their readership plummet since the companies implemented those changes.