I was looking up a counselor's phone number and noticed that the agency is dedicated to serving the LGBTQA community. I wondered "Is it a community?" Up in this neck of the woods, gays and lesbians have set events they interact in, but don't generally hang out much. I don't know about the other subgroups. Maybe at colleges it's a thing.
Racial, ethnic, and religious communities have varying degrees of solidarity, depending on location, and the term clearly has meaning in some places. There is an adoption community, I suppose, though most who are eligible don't belong. Various illnesses and conditions describe having communities, but I get the impression those are also not so cohesive. Hobbyists have a certain camaraderie that might qualify them for the Civil War re-enactment community, or extreme skiing community.
I think it is sometimes used in exaggeration, to pad the numbers or influence, or to reassure members that they are not alone, but part of a caring group. That seems sensible enough, but anything that is not strictly accurate can have its downsides.