A few weeks ago, there was an interesting interaction on Slate Star Codex (found via Brute Reason). Apophemi complained that they felt excluded by the dispassionate discourse on triggering subjects within the Less Wrong/Rationalist community, and Scott Alexander defended the rationalist community. I don't have anything substantive to say on that topic, since I don't regularly pay attention to Less Wrong, and also I don't experience triggers. But many interesting points are brought up, and here I discuss one.
One of Apophemi's complaints was that people on Less Wrong would reject words like "racist", "sexist", and "ableist" out of hand. I can believe this charge, because I've seen lots of people say things like that. I recall one time someone declared "homophobe" to be a "poisonous" word, and then they proceeded to ignore any other words I had said. Also on the large scale, there is a whole segment of Christians who say that they're not homophobic, they just think homosexual acts are sins under God. (I'm focusing on "homophobia" since I have more relevant anecdotes, but my points could easily apply to the other words.)
Scott Alexander offered a general rationale for rejecting these words. If you use a word like "racist", you are biasing the discussion with a loaded term. It is reasonable to ask someone to taboo their words, to make sure that their argument is based on substance, rather than equivocation.
Personally, I think feminist/anti-racist/queer/disabilities activists can and should rise to the challenge, when necessary. If someone is being homophobic, then there is a way to negatively describe their without using the particular word "homophobic".
For example, when I talked about how terrible the Catholic Church is, I did not use the word "homophobic" at any point. I think "homophobic" is a rather squishy term, and therefore I am not committed to the claim that anything is or is not homophobic. I am much more committed to the idea that the Catholic Church has terrible attitudes about LGB people, no matter how you describe them. If you came up with any single word to describe the Catholic Church on that axis, I think it would become a bad word faster than you can say "euphemism treadmill". This is basically why the phrase "hate the sin, love the sinner" has negative connotations. Christians used that phrase to positively describe their views, but since their views are widely regarded as terrible, the description became pejorative.
I do not propose that everyone follow my example in all situations and contexts. It's useful to have a shorthand word for "negative or harmful attitudes towards group X", and we're not going to find a non-pejorative word to do it. The fact of the matter is that I could call the Catholic Church homophobic, and many of my readers would agree, and it would be a succinct summary of my opinion.
It's also worth noting that not every discussion is about mutual enlightenment. It's cynical, but true that many arguments are really about power. If I call someone homophobic, and they accuse me of shutting down the conversation with a "poisonous" word, maybe that's exactly what I'm doing. And maybe I'm right to do it, because life's too short to argue with everyone. I openly admit to occasionally being mean to commenters on this very blog, because some commenters are just more valuable as comic relief than as sources of ideas (present readers excepted).
But there are a few contexts where "homophobic" is not a useful term. If someone says, "I'm not homophobic, because of [definition hair-splitting]. I just believe [terrible thing]," joining in the hair-splitting argument may not be the best strategy. They admit to believing [terrible thing], so what do the technicalities of squishy words matter?
An example of application: A few months ago, Conan' O Brien made a joke about a Muslim superhero character being one of many wives, and people on Friendly Atheist argued over whether it was racist. The joke was all about applying a negative stereotype to a character expressly created to counter such stereotypes (by an author who personally experienced the stereotypes). This is not defensible regardless of what you call it.
Finally, I suggest that a similar approach should be taken towards other feminist terminology as well. "Privilege", "Patriarchy", and "social construct" have underlying meaning (or they don't, if used improperly). If people split hairs over the definitions of those words, the underlying thing being described remains the same.