I’ll disagree.
Limud HaTorah, by definition, is asking your Rabbonim to explain why P’sak is what it is. Only through “Riska D’oraysa” can we come up with a mehalch.
As such, if someone asks “why” to be M’kanter, the OP is correct. However, a Rov (or gadol) is MECHUYAV to explain his p’sak to his talmidim (and everyone in Klal Yisroel is a talmid of the gedolim), so that they may learn from it.
Torah he V’lilmod Ani Tzarich.