I don't like the assumption of the author you must have observed these architectures in action. Nor does he think you can learn from a 4 year old architecture t

I don't like the assumption of the author you must have observed these architectures in action. Nor does he think you can learn from a 4 year old architecture that was in place when you joined the company. Nor can you read books and papers published about companies' architectures. He touches on this point only to reinforce that you can only learn by experience, which is at least partially incorrect, even if I agree its a fantastic teacher. It's a nice bit in humility and a reminder of the length of time it takes to reveal major effects of architecture decisions but it paints a bit of a false hopelessness.