“Frankly, I have a hard time seeing how anyone can disagree with this”
I don’t think anybody disagrees. I think everyone will acknowledge that someone who is smart and very knowledgeable in Torah can give good advice and inform you about what the Torah sources say on a given topic. The issue is when this said person issues a statement, without providing a Torah source (or where other people bring in conflicting Torah sources) and people say that these statements are binding on klal yisrael as determined by the percieved stature of the issuer of the statement.