LF: I think you have some basics right but you are taking things too far. Any Chacham Shehigia L’hora’ah is allowed to argue on any other Chacham Shehigia L’hora’ah, even if one is greater than the other. The Gemara says that a Chacham Shelo Higia L’Hora’ah who Paskens destroys the world. You are extending things farther and saying there is a subgroup here of people who no one is allowed to argue on. That group has not existed since we lost the Sanhedrin HaGadol.
No one is claiming that national matters of importance shouldn’t be decided by Talmidei Chachamim or that the biggest Talmidei Chachamim shouldn’t handle the biggest Shailos. Some just think that the concept has been extended too far. To quote the Gemara, the Torah gave each of us permission to say that something is Kosher, etc. There are parts of life that we are expected to live on our own.
I’m curious, by the way. Why do you think that Amoraim can’t argue on Tannaim and Rishonim can’t argue on Amoraim?