For why it’s ablism, and also just busted: because phobias are real things. They qualify as disorders, if you want to use that term, it’s in the DSM and all that. I hate the DSM, but it’s there. I also am uncomfortable with the term neuroatypical, but phobias almost definitely qualify under the label.
A genuine phobia can have serious effects on a person’s life. Things like homophobia and xenophobia are not the same thing, but are being compared to that. This is not fair on people who have genuine phobias.
Something that I hadn’t thought of before but eateroftrees pointed out, this also makes things harder for people who actually can develop genuine phobias as a result of internalizing hatred. Although not for everyone, for some people the self-acceptance process can involve panicking, even for people who have friends who are gay/bi/trans/feminine and support those friends, because of the heavy anti-gay, anti-bi, anti-trans, anti-feminine messages in this culture. This is not the same as mistreating people for being gay or bi or trans or feminine, and conflating it with that only makes it harder for people who experience this.
This also has a very real damage to the communities. Don’t believe me? Look up “Gay Panic Defense” and “Trans Panic Defense”. The idea that hating gay people and trans people is a phobia adds to the validity of these. It sets up an ideology where a cis man on trial for brutally harming a trans woman who made no moves to harm him save for self defense can say “I was afraid for my life”, and a jury will believe it because they keep being told that people like him are severely afraid of trans people instead of being told that people like him hate trans people.
I’m pretty bad about not recognizing ablism, and this is no exception. I had to read this through twice before it clicked.
There are much better words out there that don’t end in -phobia. I use words that end in -centrism, to convey the idea that certain people think a certain way of being is (and even should be) what our society revolves around. Ciscentrism, binaricentrism, heterocentrism, etc. You can even put a dash in the middle of the word if it makes you feel better, like masculine-centric.