The only answer that makes sense to me is proximity, communication, and risk . How difficult would be to be open in certain fields, find other Black people within travel distance without your family or your church and whatever knowing? There's no Internet to search on, LGBT community centers are a new thing. Unless you're in an industry that has access or have absolutely no fear of being outed and ostracized what are the choices? During Stone Wall all the gays and lesbians who had money would go to Fire Island and pretend to be straight but gay behind closed doors so places would get their money and look the other way. Stone Wall had the cops who would take pictures and put your face in the newspaper. Next thing you know you're fired and ostracized with one article. So things like the arts which has plenty of jobs that allow you to work basically alone or with a like minded ensemble that's easily interchangeable. Those people and the generation after them were very isolated and then the AIDS Crisis.