It's knowledge you get by actually working in the field rather than reading about it in reports and white papers. It has value, it's not everything, but it is important. What actually needs to be in place are independent auditors who aren't linked to the industry and can't profit from it to review the decisions of these agencies and have full access to all data, including engineers who say "yo this is a bad idea". I have been that engineer a few times with mixed results, sometimes people listen, sometimes they don't. Never on the level of the FAA/Boeing fiasco but still it does happen all the time, everyday. That's why rules to prevent fraternizing between agencies like the FAA and Boeing are important. It's a lot harder to be tough on friend/colleague than it is someone who you don't know and are auditing.
The _entire issue_ is capture of those who regulate making planes by those making planes. Disallowing transition from one to the other seems like a good idea.
