Samo was expressing a personal opinion. You were appealing to authority for legitimacy. Apples and oranges.
You misinterpreted it. I don't have personal opinion on this site's material, but maybe other people have. For example on Amazon. I didn't expect that Samothec will acknowledge that opinions on Amazon are more correct than his own. So maybe rather I was appealing to social proof, to make it legitimate that I don't have to agree with his opinion. And social proof is about opinions, too. Apples and apples.
By the way, I read your previous statement inaccurately. You wrote: "Oh, well then, he must be an authority.
". I somehow read it as "Oh, well then, it must be an authority.
" (it=Amazon) So I had to balance it with something.