It is certainly true that who says a thing is just as important as what is being said. I can rant all day about sexual liberty and only those who already read my stuff will care. If a soft spoken conservative churchgoer made the same argument though a lot of people would sit up and listen. Recently I found an article talking about some studies that found exactly that; people surveyed based their opinions very strongly on how the writer identified. In particular people who identified as feminists or environmentalists were given much less credit when talking about their particular areas of interest.
(Of course we should note that these studies were small and conducted on the usual pool of bored undergrads so all the usual problems apply yadda yadda you know the drill.)
This is a real issue with identifying publicly as an activist or supporter of nearly any cause. It is helpful because it provides visibility and gives others a place to work towards but it tends to makes anything said by that person less impactful to others. There is something seriously powerful in the action of identifying explicitly with a group that makes others deeply mistrustful. I am confident that people would have the same sort of reaction to a banker talking about how the government needs to loosen financial control over banks - unless the person already buys into that argument they will dismiss it out of hand.
It makes me wonder about explicitly identifying myself as an environmentalist or a feminist. My views definitely support those terms and yet I wonder if that doesn't end up causing people to discount what I have to say on those topics. Essentially it boils down to the question of whether or not that explicit identification helps convince others of our point of view. Clearly environmentalism and feminism are important but how important is the label?
I don't really feel especially attached to labels personally but this is probably due to privilege. Both labels that I choose to adopt (gamer, geek) and labels that have been stuck to me (male, straight) just don't particularly feel important to me; this is obviously pretty easy when you can't imagine somebody trying to deny that label and many folks don't have that luxury. Of course part of it is also just who I am - being fifty feet tall and made of steel (metaphorically speaking, one would assume) really helps when you want to ignore the verbal barbs that might be tossed your way.
Maybe I would feel differently if I conducted my life differently, if I spent more time charging the barricades rather than valiantly trying to slay the trolls. Could be that doing so makes the label a lot more powerful but I can't say for sure.