What you're talking about is a very specific area of patent law: Patents on manufacturing processes. The assumption is that without the patent the knowledge necessary to reproduce the products made with the method would be extremely difficult or impossible. This is nonsense in this day and age.

Modern engineers of varying sorts can reverse engineer basically any process and underpaid employees who know the secrets can be easily poached. Therefore, the entire concept of patents existing for the sake of disclosure falls flat on its face.