I would suspect folks staying in the closet was more about not wanting to feel different than being ostracized. Granted I can only talk from personal experience, but I grew up with several extended family members who were obviously gay, if not openly gay (though I believe they were likely all openly gay as none of them tried to hide it). It was one of those things where everyone knew it, but no one talked about it, and there wasn't any problems.
None of the heteros announced they were having sex with the opposite sex, and none of the homos were announcing that they were having sex with the same sex. We all knew, because you can see who everyone is hanging out with and who all the significant others are, but no one felt a need to beat anyone else over the head making sure everyone knew what holes they were putting their dicks into at the end of the day.
My anecdotal story aside, we also had people in pop culture as well back in the day who were openly gay, or TV/Movie characters who were gay, and I don't recall anyone making a big deal about it.
As far as gay folks getting movie roles or what not, it goes back to what was mentioned earlier. If you can't portray the character that's being cast, you won't get the role. If you can, you'll get it.