It’s the concept of it functioning as an interconnected community. That’s why I don’t like how it’s called an LGBT “community”. If you said that all women are in the “female community”, that would barely make sense. What do they all collectively have to do each other besides being female?
It’s a similar deal with the “black community”, or the “Latinx community”, it’s implying that you’re obligated to stick to your own kind or else you’re deficient by not treating complete strangers as an extended family.
They complain about gatekeeping and yet being in the clubhouse is still somehow exclusive and authoritative, as if you have divine right to rule over the cishet peasants and serfs by proclaiming you’re a queer.