"Relying on CVS and Subversion [...] with access controls limited to the select few committers makes it very difficult for those on the fringes to get more involved."
If you have an idea for a new feature in the morning, you can write it and push it to the production servers before lunch. And when you can do that, you have more ideas.
the most effective learning situation is one where a small number of apprentices work alongside an even smaller number of journeyman, who are receiving guidance from a master craftsman