Earlier quoted context omitted.
The Facebook app is like Microsoft Word. Everyone only uses 20%, but it's a different 20% for each. The app is a hojillion megabytes, and serves literally billions of users. There's features in there that addresses some specific niche in Africa for "only" 50 million users, that some sub-team of a sub-team is tasked with maintaining.
Microsoft doesn't use an abstraction to create Word for Mac OS. They have shared code, yes. But they are different products with different user interfaces to match their respective platforms. I'm not sure why mobile is so different that one needs a platform abstraction if you've already got a bazillion developers working on the product. Of course, Facebook does benefit by owning that abstraction making it exactly wha…
For Word and Excel for iOS and Android they use... React Native [1].
[1] https://blog.appfigures.com/microsoft-goes-all-in-on-react-n...