This is not how it worked at all. There were not competing systems, there were not proposals, there were only practices, and there was certainly not critical ev

This is not how it worked at all. There were not competing systems, there were not proposals, there were only practices, and there was certainly not critical evaluation of what worked best. There was a ton of path dependence. We use notation for the same reason they use Chinese characters in China: partly for cultural prestige reasons, but primarily because it would be such a hassle to switch, with a billion people having invested so much in learning it and so much being written in it. (It's interesting that China should go the exact opposite way of cumbersome inherited complexity in their own music notation system, which as I've noted elsewhere is an undeniable pedagogic success but struggles to get accepted as more than a stepping stone to "real" notation)