Bringing up privilege shouldn't completely shut down a discussion, but rather give context to it. The context is important, because when people are making an entire argument related to a pretty big issue based completely on their own experience... well, anecdotal evidence doesn't count for much. Even when you get a room full of people who decide to make an argument based on a collection of personal experiences... the plural of anecdote is not data. Data, though, provides a much better basis for large-scale decision making when stakes are high. I'm not trying to defend the rhetorical strategies of people on tumblr or buzzfeed (or anywhere else on the internet)- I'd tend to disagree with comments about people using and framing discussions of privilege/intersectionality for their own pre-determined ends.