I think people have the misguided idea of looking to FAANG for best practices, but mostly these are monopoly companies that have very high profits and little competition. Quality of their products is beside the point and they can afford to hire an excessive number of very expensive developers in the homeless capital of the world because... they can!

Nobody would point to Epic, Cerner, Salesforce, Adobe or Microsoft for "best practices" and they shouldn't do that for Facebook either.