As for why asexuals are considered part of the LGBTQ+ community, a sexual orientation regarded as "weird" or simply not recognised/accepted by the majority would surely want support from orientations suffering similar fates...
Perhaps, but when the discrimination arises because they are assumed to be homosexual, joining a group that is predominantly populated by and almost solely recognized for homosexuals may not be the best strategy.
Are you happy with simply LGBT? When you read that acronym, what do you think of?
Today, humans are the most advanced species on the planet. When I was younger, something they taught me in biology was that all species have 2 basic goals: survival of self, and survival of species (reproduction).
By that flimsy definition, then the animals and plants we raise for food are far more successful than humans.