With its front page composite photo of Bill de Blasio sporting Donald Trump’s coiffure, the New York Post reported with no small amount of glee that the progressive New York mayor sounded “positively Trumpian” in private emails blasting the local news media.

De Blasio has responded by going on the offensive against “corporate media”—and really, he doesn’t sound so much like Trump as Bernie Sanders. The Vermont senator also assailed the news media as part of his 2016 presidential campaign. He was more subtle and fact-based than Trump, but the bottom line was that he, too, argued that large segments of the news media can’t be believed. The left, as well as the right, has helped to de-legitimize the news media.

There is a grain of truth in complaints from both sides. Rupert Murdoch’s New York Post is Exhibit A for how a new corporate owner can impose his political slant on a news organization from Day 1. And conservatives are right that most people working in the news business, especially on a national level, are liberals and tend to know only other liberals.

But in both cases, this has morphed into expansive conspiracy theories that malign the credible news reporting that democracy requires—which, by and large, is what mainstream news organizations produce. The right had led the way here, as seen in the historically large partisan divide in public confidence in media coverage, but is not the only offender.

Sanders summarized the left-wing case in “Corporate Media and the Threat to Our Democracy,” a chapter in his 2016 book Our Revolution: A Future to Believe In. His evidence for the media’s failure is that he couldn’t get coverage for various news conferences that dealt with substantive issues. But the issues he cited were in fact getting coverage in major newspapers, even if his press conferences weren’t getting the attention he wanted.

A case in point was a media event he held in New York City to talk about dilapidated conditions in public housing. “There was almost no coverage of this issue,” he complained. But actually, the New York Daily News had exposed this problem in one article after another. The ongoing neglect of the housing projects was already well known to the public precisely because of the “corporate media.”

Similarly, Sanders bemoaned the lack of coverage for a 2013 news conference he held with AARP and other advocacy organizations about proposed cuts in Social Security. “It was not of interest to the corporately owned media,” he wrote.

But that didn’t mean there was no media interest in the fate of Social Security. There had been stories in the “corporate media” in previous months about how liberal legislators and groups such as AARP were trying to head off changes in Social Security. At the time, President Barack Obama was willing to revise the program to get a deal with Republicans on extending the federal debt limit. Sanders was quoted in a Washington Post story. He had a letter to the editor in The New York Times, agreeing with an editorial it had carried on the subject.

And yet, in his book, he insisted that “corporate media” were not interested in the public’s retirement payments.

There are echoes of Sanders in de Blasio’s critique. “I think it’s the corporate media that in too many ways is not telling the larger truth of our society, not just the interest of a corporate ownership structure,” the mayor told reporters Friday in a rare mayoral visit to the press room in City Hall, Room 9, on the other side of the rotunda from the mayor’s office, where he blasted the work of the reporters there. “The truth is not being told, or it’s being wildly biased.”

The occasion for this visit was the city’s release of more than 4,000 pages of internal emails between the mayor’s office and a public relations consulting firm, BerlinRosen, as a result of a unanimous May 1 records-access ruling by a five-member appellate court. One thing to be said for corporate ownership is that the plaintiffs in the lawsuit—Spectrum News NY1 and the New York Post—had the resources to spend three years fighting de Blasio in court to win release of these public records.

As a former City Hall reporter—I covered Mayor Edward I. Koch throughout a 1980s corruption scandal, and later, Mayor Rudolph Giuliani—I found familiar scenarios in the emails. De Blasio and his aides agonized over the coverage, as previous administrations had, and contrived to spin it their way. The reporters mostly asked for comment on stories they were working on.

The documents offer a valuable look at how outside interests—PR man Jonathan Rosen and his firm, which has many real estate clients—install themselves in City Hall. It’s an old New York story, for sure, but it created an appearance that troubled the judge who initially ordered the emails released. “Rosen is a private citizen whose private interests may diverge from those of the City in connection with his representation of his private clients, some of whom conduct business which may be impacted by city policies, such as zoning matters,” State Supreme Court Justice Joan Lobis wrote.

That may be the heart of the matter, but I can understand if reporters focused instead on an email in which de Blasio commented coldly on the possibility of a shutdown at the Daily News. “And that would be good for us, right? Or would that make the Post more dominant?” he wrote. “Or, conversely, would it hasten the demise of the Post—prob just wishful thinking.”

What was more revealing to me is the argument de Blasio became embroiled in with Bloomberg News City Hall reporter Henry Goldman when he visited the press room on Friday.

Goldman complained that de Blasio had derided an accurate 2014 article he wrote saying that an unexpected $4 billion budget surplus would help municipal workers in coming labor talks with the mayor. “You said, `Oh you can’t believe that. Look who published it: Bloomberg News,’” he said.

“Are we living in a dream world where we think the owners of the media don’t exert influence, is that what you’re saying to me?” de Blasio answered.

That’s the broad-brush “corporate media” critique—and in a case when it doesn’t seem to make sense, since the existence of a big surplus is a boon for labor. Besides, Bloomberg News happens to have numerous awards for exposing corporate conniving, including a 2015 Pulitzer Prize for explaining how companies avoid taxes by changing addresses.

A more telling critique of corporate media in New York than the self-interested one de Blasio has offered might have been to note that Mayor Michael Bloomberg secured the approval of the the owners of the News, Post, and Times before setting out to change a term-limits law that voters had twice approved so that he could run for a third term. (When one reporter later asked Bloomberg—who’d claimed his leadership was indispensable after the 2008 market crash only to tout his accomplishments as he ran for that third term—why he was still needed if things were going so well, the mayor hissed: “You’re a disgrace.”)

There is a critique to be made of the corporate media, of New York’s “tabloid culture,” as de Blasio puts it, and also of biased or short-sighted reporting. But it won’t be made properly through wild charges that serve to de-legitimize honest reporting.