I think both can exist at the same time and still be good. Like how this sub is combined LGB, but there are also subs exclusively for gay men, lesbians, and bisexuals.

LGB combined, like LGB Alliance, focus on our needs as a group. We are all same-sex attracted individuals, and that is distinct from opposite-sex attracted individuals.

At the same time, each letter of L-G-B does have their own shared experiences, and should to be able support one another in that without taking away from the others.

Lesbians and gay men are both homosexual, but their experiences of homosexuality can and will differ since men and women are different. So they should be able to come together to support their own people (men-or-women) exclusively also.

Lesbians and bisexual women are both same-sex attracted, but bisexual women also like men. Each group of women should be able to have their own exclusive space where the differing sexuality of the other isn't overtaking or silencing their needs.

Same for gay men and bisexual men. They have commonalities within their same-sex attraction, but bi men also like women. So its OK for each group of men to have their own spaces without intruding their different sexualities onto each other.

We can all come together as a whole in our shared LGB group, while we can also have a unique supportive group for our individual sex-based attractions.

These unique groups - even us as LGBDropTheT instead of LGBTQP2SIAA+ - form BECAUSE the rainbow expanded into everyone and everything being lumped together as a whole. The expansion has taken away all agency from the individual sexualities because it blurs everything together.