Mark Zuckerberg had a strong message on Facebook's year-end earnings call Wednesday: We know we have some problems with our product, but we're going to fix it, and, long-term, the fix is going to be a win-win for our users and our shareholders.

The CEO revealed that early changes in the nature of the videos it shows to users in their News Feeds had a marked effect on consumption in the fourth quarter of 2017, with average time spent per day falling by around 5 percent. The video changes were just the first of a series of planned tweaks Zuckerberg has announced, the collective goal of which is to encourage the kind of "meaningful interactions" that contribute to emotional well-being and a sense of "time well spent," while combating things like political polarization and the spread of false information. Facebook's daily average user total in North America fell slightly in the quarter, the first ever such dip.

Asked whether the changes still in the pipeline could further drive down Facebook usage, Zuckerberg admitted they would--but suggested Facebook's advertisers and investors have nothing to worry about. "I do think that is likely going to continue this trend of decreasing passive consumption, but if we do our jobs well, it should increase the number of meaningful interactions people have, and we think that's going to be positive for our community and for our business," he said.

But evidence abounds that it's not going to be that easy. And that Zuckerberg's stated goals may be incompatible with a Facebook that keeps growing like it always has.

Take the push to prioritize interactions over passive consumption. As Zuckerberg was speaking to Wall Street analysts, many Facebook users were seeing a Trending News module full of posts claiming the crash of an Amtrak train in Virginia was a plot by Hillary Clinton to murder political opponents or a "false flag" attack by "deep state" elements.

Posts like that reliably generate lots of interaction. The people sharing and commenting on conspiracy rumors no doubt find them meaningful. Maybe muting content like this is part of the product road map that hasn't been implemented yet. But it's not clear on what basis that could be done. (A Facebook spokesperson told The Daily Beast that the stories trending in the wake of the Amtrak crash made for "a bad experience, and we're going to work to fix the product.")

Indeed, when pressed, Zuckerberg indicated that Facebook's heuristics for what sorts of content to promote won't be all that different from what they've always been.

"I think there's this myth we design News Feed to optimize for time spent or likes or comments or what have you," he said. In fact, he said, Facebook also surveys panels of users to ask them what they want to be shown and weights those answers heavily in its algorithm. "We've done this for years. We ask 'What's the most meaningful content you've seen?' And we design our systems to get to that ground truth of what real people tell us is a high-quality experience."

In other words, all the stuff that's flourished on Facebook over the past few years--the fake news, the polarizing propaganda, the viral frippery, the stuff that Zuckerberg has promised to do something about--has proliferated even as Facebook has been actively trying to filter for what's meaningful. That suggests there could be diminishing returns for any future efforts to increase the "meaningfulness" quotient.

As for cutting down on fake news, Facebook's plan is to establish which news sources deserve wide promotion by...surveying its users. "People are smart," Zuckerberg said. "They know what they want and they know what's good and they can tell us that." A strong signal of an outlet's quality is when many users say they don't read that outlet but consider it trustworthy, he said.

Think about that. The best way Facebook has of determining what news isn't bullshit is asking people for their opinions about news they don't read.

Meanwhile, Facebook has been attempting to stem the ebbing tide of usage through aggressive tactics to re-engage users who've quit or become less active. Some of these methods are borderline deceptive: Bloomberg reports that some idle users receive an email from Facebook suggesting their account is under attack by hackers, prompting them to log back in to secure it. I recently noticed that Facebook's email notifications offer misleading teasers in their subject lines hinting at content in the message body that, once opened, isn't there, only an invitation to log into Facebook to see it.

Here's a thought: If Zuckerberg is serious about making sure every user considers the time they spend on Facebook to be time well spent, why not start by respecting the decisions of users who have made it clear in no uncertain terms they don't have time to waste? 

But doing that, of course, would require him to accept the possibility that Facebook might have to choose between being bigger and being better.