If you've ever wondered why Mark Zuckerberg hates Snap (NYSE:SNAP) so much, look no further than eMarketer's latest estimates on social media engagement across demographics. The figures show that Snapchat remains more popular than Facebook (NASDAQ:FB) and its Instagram service among U.S. teens (ages 12 to 17).

The good news is that Facebook engagement remains strong across all other age groups, including millennials, Gen Xers, and baby boomers.

Person looking at a friend's Facebook profile on a smartphone

Image source: Facebook.

Losing traction with teens

eMarketer's figures show that Facebook will have just 11.5 million U.S. teens on its platform this year, down from 12.1 million last year. Facebook is expected to continue losing users in this demographic, and is expected to have just 9.3 million U.S. teens on the platform by 2022, according to the estimates. In contrast, Snapchat's U.S. teen user base will swell this year to 16.4 million, topping the 12.8 million U.S. teens that use Instagram.

Instagram has enjoyed incredible success in replicating Snapchat Stories, which has proven to be a remarkably popular format for sharing content. Overall, Instagram now has 400 million Stories daily active users (DAUs), making that feature alone more than twice as big as Snapchat's entire platform. Snapchat also recently reported its first user decline, which it blamed on the controversial redesign.

But Stories, which Facebook also brought to its flagship platform, has not helped bolster engagement among teens. eMarketer senior forecasting analyst Christopher Bendtsen points out that while Stories is driving overall growth for Snapchat and Instagram, the feature is "not helping Facebook retain younger users." U.S. teens continue to abandon Facebook, or in many cases never sign up at all.

The other demographics are stable for Facebook, with an estimated 58.5 million millennials in the U.S. on the platform. On top of that, eMarketer estimates that there are 45.1 million Generation X users and 31.9 million baby boomers on the social network. Snapchat has little traction in these demographics, with just 3.8 million U.S. baby boomers shooting ephemeral photo messages.

Diversify, diversify, diversify

Declining Facebook usage among U.S. teens has long been a concern among investors, but those fears have also been arguably overblown. The social network has made some efforts to build its pipeline of users, such as recently releasing a controversial version of Messenger designed for kids.

But overall, Facebook's user metrics -- and financial results -- remain resilient, even in the face of a seemingly endless string of data privacy scandals. Facebook does not break out demographic details of its user base -- data that users submit and Facebook barely verifies anyway -- but it now has over 2.2 billion monthly active users (MAUs) globally. That doesn't include all of the other services that Facebook owns.

The conglomerate strategy that Facebook has adopted, in which it owns and operates a growing portfolio of distinctly branded social media platforms, has worked amazingly well. Another benefit of that strategy? By diversifying, Facebook is also reducing the risk associated with any one platform losing popularity among any one demographic. Those users are likely end up using another Facebook-owned property, whether they realize it's all part of Zuck's sprawling empire or not.