I am pansexual and I think that saying that pansexuals are not considered a part of the gay spectrum IS erasure. The joke in that post was exactly about the erasure that pansexual, asexual, bisexual, and aromantic people face. That they're "the gay people that can't be seen." The fact that you think that pansexual, asexual, bisexual, and aromantic people are not a part of the gay community is erasure.
There literally isn't a line between straight and gay that says how straight or gay you are that other marginalized sexualities fall on.
Gay literally is a word for homosexuality. It's a term for solely being attracted to people of your own gender.
Bisexuality is attraction to people of your own gender and one or more other genders.
Pansexuality can be included in bisexuality, and is the attraction to all genders.
Asexuality is no sexual attraction to people, although this can include grey-asexual, demi-sexuality, and others.
Aromanticism is based on lack of romantic attraction. You can have different romantic attractions to your sexual attraction, so you can actually be aro and gay.
Bi, pan, and ace people are not a sub culture of homosexuality. We are as much our own sexualities as hetero or homo people.
I think what you're you're trying to say is that you're a part of the queer community, or LGBTTQQIAAP community, or MOGAI community.
In a lot of situations people classify bisexual and pansexual people as gay or straight, depending on whomever they happen to be dating, which effectively erases the sense of their sexuality and attraction to other genders.
