Amazon does a good job of training new hire on the 'Amazon way'. Amazon does 6 pagers, they do design docs. Amazon does SOA. Amazon does not use relational databases. Everything has an API. Because of the 'Amazon way' and the training they do new team members understand at least some of the context and expectations.
Is it the best way? Probably not but no one knows what the best way is anyway. At least they have a way. Saves a lot of effort compared to every new hire relitigating the process and architecture.