Facebook COO Sheryl Sandberg said Thursday that Facebook is not a media company. Jonathan Leibson/Getty Images Sheryl Sandberg and her peers in Silicon Valley may not want to admit this, but Big Tech has become Big Media.

And with that change comes major responsibilities — ones that the tech giants are currently shirking.

Sandberg, the chief operating officer of Facebook, made news this week when she steadfastly refused to acknowledge in an interview with Axios editor Mike Allen that her company is in the media business.

She may be the most prominent denier of Big Tech's new role, but she's not the only one. Sandberg's colleague, Andrew Bosworth, Facebook's head of consumer hardware, echoed her position on Twitter this week.

Their argument goes like this: because tech companies generally don't employ journalists who report and write the news, they can't be media companies.

But that position ignores the facts of how the media business has changed and how people today consume news, information and entertainment.

Facebook's news feed has become what the front page of the newspaper was for older generations of people; at least 66% of the social network's 2 billion users rely on it as a news source, according to a 2016 Pew study. Meanwhile, consumers turn to Twitter for breaking news, and they search Google for news updates.

But consumers didn't just change their media habits on their own. The tech companies argument also conveniently disregards how the big tech companies themselves have purposefully and intentionally tried to become go-to news destinations.

Facebook purposely designed its algorithms to customize users' news feeds to show them the stories and other information they're mostly likely to engage with, whether by clicking on a headline or typing in a comment. Google not only operates Google News and touts live news events on YouTube, but it's even altered its core search feature to show links to relevant articles above search results when users search for newsworthy items. And Twitter has launched numerous features, including a "What's Happening Now" page and a "Moments," to highlight news stories and information.

Perhaps most damning to Big Tech's line of argument is the impact those companies, particularly Facebook and Google, have had on the rest of the media business. Advertising is the lifeblood of media companies. And with ads increasingly shifting away from traditional media such as newspapers and television to digital ones such as the web and mobile devices, old media companies have been trying to move in that direction too.

But they're failing, thanks to Big Tech. Last year, Facebook and Google accounted for 99% of all the growth in digital advertising, according to one estimate based on Interactive Advertising Bureau data, leaving peanuts for the rest of online media platforms. That dynamic will almost certainly repeat itself this year.

And that's not to mention Big Tech's broader effort to become Big Media. Facebook, Google and Twitter, as well as Apple and Amazon, are all all aiming at Hollywood by investing in originally produced entertainment videos, television shows and movies.

In a very real way, Facebook and the other companies are deciding what news millions of people see. There's just no disputing the fact that Big Tech has massive influence over the way people consume media.

But it's also become increasingly clear that the big tech companies aren't shouldering the responsibility that comes hand in hand with that influence.

The denials from Sandberg and others about even being in the media business are just a piece of that. A bigger, more important example is how the companies have reacted to the growing pile of evidence that propagandists linked to Russia manipulated their sites and systems in an effort to influence last year's election.

In the days after the election, Facebook CEO Mark Zuckerberg gave his infamous "pretty crazy" comment about the notion that his company influenced the result by distributing propagandistic fake news. (He recently took those comments back.) While Google CEO Sundar Pichai acknowledged that such fake news could possibly have swayed voters and said the company needed to crack down it, his company and the other members of Big Tech, have done little to solve it 11 months later.

And it's not clear if the tech companies will ever fix the fake news and propaganda problem on their own, despite the public outcry. In recent months, executives at Google and other companies have argued — privately — that the problem was just too big to solve. Much of the value these companies believe they have comes from allowing users to post pretty much whatever they want to their sites. If the companies were to more thoroughly police what users post, they worry they would lose that openness and undermine their sites' appeal.

But Big Tech will likely only be able to duck from its duties for so long. If it won't accept the responsibility that comes from it's transformation into Big Media on its own, it may be forced to.

Already there are rumblings among different governments that they may step in. A pair of senators concerned that Russian-backed groups surreptitiously tried to influence last year's election are working on a bill that would force companies like Facebook to track and, in some cases, publicly disclose the purchasers of political ads. Meanwhile, the UK is considering formally reclassifying Facebook and Google as media companies, which would subject them to new legal responsibilities.

So whatever Sandberg might say, it's clear that tech has taken over media. And Big Tech is running out of excuses for why it should see the benefits that go along with that change — but not bear the burdens.