I think what the author implies is that people should use trusted and vetted crypto libraries, and rollout their own encryption primitives based on some documen

I think what the author implies is that people should use trusted and vetted crypto libraries, and rollout their own encryption primitives based on some documentation they read from who knows where. Look at OpenSSL for example, even though the people who work on the project know a lot about crypto, they still make big mistakes. Now imagine the average developer trying to build crypto from scratch.