I agree with your conclusion, but not exactly for the same reason. Those projects are huge, there is never really small group of people working on something, it

I agree with your conclusion, but not exactly for the same reason. Those projects are huge, there is never really small group of people working on something, it's often spread upon contractors over sub-contractors, with people leaving and coming, over many years, so in the end the information is quite spread. Plus there is a lot of documentation (which might also be a downside, because there is a hunt for relevant information). But what I would fear is that people would feel good about it being open source, and never go to have an actual look at it. Or go for a little bit in the beginning and then never again.