I mean, technically no, since if its morally correct to allow gay marriage, which it is, it would still be true even if most gay people were brainwashed into saying no. Truth isn't a democracy. But if you mean to say that certain people have a better vantage point to understand the right answer since its something that they are more acquainted with than others, then that goes without saying. Obviously everyone doesn't have equal knowledge of everything. and obviously the right answer isn't derived from nothing but some kind of vote, which if it were it would be confusing why who was talking mattered.

But that wasn't my point. My point was that even if true, there's people who try to use this idea in principle to lend weight to ideas whether or not they actually hold up any better, or sometimes even whether or not the people they're trying to cite actually have some form of coherent consensus that someone is deriving their orientation of ideas from, and which is also objectively correct. I wasn't disagreeing that its useful, just pointing out that sometimes people (often who aren't even the ones they're trying to speak for) use it outside of the context it actually makes sense in.