I guess I misunderstood the jam requirements. The rules listed on the jam page merely say "Source must be included" and it doesn't say anything about that source being only for the jam maintainer. So until a person goes to the submission form once the game is done, there is no indication that they are not expected to share their source code publicly. I'll ask CodeMyst if I misunderstood.
So CodeMyst said that the intention in the rules was the code should be made public, and that requirement was changed only after people "didn't want to". So, I say, as if that matters, most people should still be asked nicely if they wouldn't mind sharing their code. I think that makes this jam more relevant. Just my opinion.