[NB: we discuss the word “homophobia” in more depth than words like “lesbophobia” or “transphobia” because all post 1955 “phobia [bigotry]” words that the mods have encountered are explicitly based off of the “homophobia” model.]
"Homophobia" is not the same thing as "heterosexism," and suggestions that we just replace former with the latter don’t completely solve the problem. Heterosexism posits that heterosexuality is the only valid sexual orientation and that all other orientations are "lesser." Homophobia is the hatred and active persecution of queer people. Of course, actions that are heterosexist can be called "homophobic" because enforcing a hierarchy that devalues queer people is an act of persecution against queer people. And similarly, anything that’s “homophobic” is technically heterosexist because persecuting an oppressed minority does indeed enforce a heterosexist hierarchy. “Heterosexism” is a good word to use when critiquing TV networks where all the lead characters are straight.
But what activists who claim that we “need the word homophobia” are really saying is that “homophobia” is a much stronger term than “heterosexism.” And it is, and we need to be able to have a word for hate crimes and Tracy Morgan’s rant and the fact that our youth are 4 times more likely to be homeless and unaccompanied that doesn’t sound clinical or overly-academic. But the reason we don’t jump straight to terms like “hetero-suprmacy” or “anti-queer” or “queer-hate” is because none of these terms are genuinely as pathologized and suggestive of violence as a mental illness is.
The fact is, people who have spent a large amount of time arguing that “homophobia” is an irreplaceable term are either willfully ignorant or simply frustrated that none of the new suggestions—even though all of them harken back to bigotry or hatred—can convey the stigma that “lol you’re crazy” can. “Phobia” language is a way of placing the blame on the bigot and not the culture or the people who are being oppressed. But it does this by playing off of our understanding of mental illnesses as things that are embarrassing to have, likely to result in violence, and a drain or deviation from healthy, “sane” society.