Twitter, the service, which has supplanted cable news as the center of the real-time political conversation, is rotten with abuse, harassment and disinformation. Twitter, the company, failed to fix these widely reported problems before the election, only to appear impotent as they blossomed into crises in 2016. Rampant gender-based and racial harassment was a defining characteristic of Twitter’s relationship to the 2016 campaigns. A recent Anti-Defamation League report tallied tens of thousands of vividly anti-Semitic tweets directed at journalists in the last year alone.

Yet the Facebook situation may be the clearest expression of what a transitional media environment actually feels like, and how disorienting it can be. In February, nearly half of Americans said they consumed news on the site — a figure that is most likely higher now. But the company has been widely criticized for the level of misinformation propagated through its service. In the weeks before Election Day, one of Facebook’s most visible functions was as a distributor of so-called fake news.

It is surely not desirable, by any reasonable standard, to have over a million people share a falsified presidential endorsement of Mr. Trump by the pope. But that happened this year. So, too, did the sharing by millions of people of a falsified quotation attributed to Mr. Trump in which he was said to call his future supporters “the dumbest possible group.” The story, first popularized on a left-leaning Facebook page, was convincing enough that its debunking is now being met with conspiracy theories.

But calls for Facebook to fix the problem — presumably through some sort of new editorial filtering, or prioritization — misunderstand the company and its situation. While asking Facebook to fix it is reasonable, it is probably equally unrealistic. In many ways, the company has already moved on to the future.

The fake news problem, as it has been identified, is occurring on what the company, based on its public statements and actions, would consider an old version of the network, one it seems determined to abandon. In this version, people post links to outside websites, and those websites make money from advertising. This is the Facebook most users probably know best — but it is also increasingly on the margins.