This is Facebook, a company worth billions of dollars, showcasing their last, earth shaking tech that is going to change mankind forever. Add silly hats and stars to your selfies! How could we live for so long without it!
https://ww2.kqed.org/mindshift/2017/04/13/how-play-is-at-the...
E.g. if the googly-eyes don't track right it's no big deal, but when that has been more robustified then pilots can trust real time overlays of weather radar predictions through their cockpit windows.
The iPhone has given rise to all sorts of ubiquitous technologies and applications -- so ubiquitous we don't notice them. Accelerometers weren't invented by Apple, but their pervasive use in high volume has driven the price down which has given rise to all sorts of other applications, many with the phone as bed.
Security is much better than it would be if only banks and the military cared.
Etc
It is a misallocation of effort if maximizing social value is the goal. But it's not. Profit is an imperfect proxy.
Facebook hires top talent, its sad that the top talent want to work on such problems for making profit instead of something else.
The pioneers of internet like J. C. R. Licklider had grand visions, sad that the large part of current intellect pool only want to sell out personal data and make money.