Rules of the ruling

Peace and blessings
The Rabbi explains in his book on Halacha [Moves Between the Standing] that rules like the rules of jurisprudence that appear in the Talmud are not in themselves, but rather they grow from cases, and therefore there are exceptions… and therefore the rules are not binding.
Question: A. If we have accepted the Talmud, we are not also bound by the rules, such as the Halacha of such and such a rabbi in such and such a place, even if I understand the opposite.
B. Why did the G.M. write these rules of halacha as rabbi so-and-so instead of rabbi so-and-so? According to the rabbi's method, in every dispute, the merits of the matter must be examined according to the understanding of the learner. So why does the G.M. want us to rule wholesale?
thanks.