But while Cook and Zuckerberg have some valid disagreements, each does benefit from the other's success. Nearly all Facebook users are on mobile, and nearly 70 percent of all smartphone users use Facebook, according to January data from eMarketer.
To be sure, Apple doesn't supply the majority of phones, as other platforms like Google, Amazon, and Chinese alternatives have grown. Still, many of the cheaper phones that will be used to access Facebook this year appear to be modeled after iPhones. And the allure of cheap messaging on Facebook is boosting the popularity of mobile phones, which in turn benefits Apple.
"Additionally, smartphones are becoming more widespread due to cheaper handsets and increasingly affordable data plans," another eMarketer's report said. "The number of smartphone users will grow by double digits in every market except North America this year..... A strong demand for messaging services and social media platforms like WhatsApp, WeChat and Facebook Messenger is driving the expansion of mobile internet access in these regions."
So if "connecting" everyone is Zuckerberg's primary concern, then Apple — which popularized the app-based smartphone interface — has most certainly played a role.
And in turn, while Apple certainly didn't condone any of Facebook's data woes — and may disagree with how Facebook makes money — Apple still helps facilitate that business model. There haven't been any reports indicating that Facebook broke any of Apple's privacy rules for the App Store during the recent scandal (unlike, say, Uber).
Facebook's apps may be free, but Apple has a reason for hosting free apps: They increase the attraction of iOS. If Apple were to nix Facebook, it would affect any Apple user that falls within the nearly 70 percent of smartphone users on Facebook.
App Annie estimates that consumer spending on apps doubled in the past two years, and Facebook properties have been far and away the most popular apps by monthly active users. On Sunday, Facebook was the 12th-most popular app in the Apple App Store, compared to the 24th most popular app on Google Play.