I heard a while back that Facebook's mobile apps contain some ludicrously large number of classes when decompiled. And their interview process has the same phil

I heard a while back that Facebook's mobile apps contain some ludicrously large number of classes when decompiled. And their interview process has the same philosophy you've outlined here, which I think provides the obvious explanation: since algorithms are so foundational, every developer who works on one of the apps is required to first write their own from-scratch reimplementations of all the data structures and core algorithms, and add them to the app.