I'm making a normative statement--a statement about how things should be. You seem to be confusing this with a positive statement, which you then use to claim

I'm making a normative statement--a statement about how things should be. You seem to be confusing this with a positive statement, which you then use to claim I'm ignorant of how things actually are. Of course identity does in fact matter in arguments, its about the only thing that does matter with some people apparently. I'm just saying it shouldn't. The only reason that someone would think identity should matter in arguments, though, is that the identity of someone making an argument can lend credence to it if they hold themselves as an authority on the subject. But that's just literally appealing to authority, which can be fine for many things but if you're convinced by an appeal to authority you're just letting someone else do your thinking for you, not engaging in an argument.