The problem of secrecy
The problem of secrecy is that it lets people hide their mistakes. People don't like admitting to mistakes, so if given a chance a fair number of people will actively hide them. And secrecy hides people's mistakes passively by preventing inspection of things.
Hidden mistakes cannot be corrected and cannot be learned from. Sometimes they become wrapped in layers of denial, preventing even people in the know from doing anything, because to do something would be to negate the denials.
Sometimes secrecy is passive, where people are just staying silent about how something works or what is going on. It's easy to create excuses for this.
But then, that's part of the problem. Secrecy is so easy. That's why too many people love it too often.
(This thought is probably not unique to me.)