Fear and Greed. Fear of being left out. Greedy for recognition and wealth. The two biggest drivers of human behaviour that cannot be left as the elephants in the room.
At some point in a project altruism wears off in the face of a huge commercial hit and the case of "fool me once shame on you, fool me twice shame on me" comes into play where people start to clam up rather than share their best ideas. If we don't address this people will come to read and watch in order to take away ideas rather than leave their own.
I have no idea how to tackle this but I am sure that some behavioural psychologists will have some great input.
Maybe it is just a rule of engagement like hackers groups have. That is a style of community that this community could possibly learn a lot from. It's more like a culture than an organized group.