A thing that some of the conversations from 2000 reinforce is that the OGL has never been about the legalities, it's been about trust and confidence. People used it because they trusted it (and trusted the intent behind it at the time) not because they had sat down and compared it to GNU or other open license schemes at the time. They did not jump to CC when it offered better clarity and legal support. That stuff's for nerds - they just wanted a brand they could trust, and that was the OGL.