All I have to say is that Hayek knows precious little about engineers. Yes, they can be somewhat obtuse about things outside their technical interests, but generally their jobs require them to pay attention (even if more attention than they would like) to human factors, costs, uncertainties, etc. Rarely is the task as well-specified as he thinks, and rarely is the entire design under one person's control. I share his dislike of social engineering, but engineering is not what he thinks it is.
On the other hand, chapter 11 opens with a sentence that I can appreciate:
"Never will a man penetrate deeper into error than when he is continuing on a road which has led him to great success."
I look forward to reading the rest of it.