Are you watching Mad Men? You have not been getting a truly balanced view of what it was like to be gay in advertising in that time period. I was there. There were plenty of gays who, like me, didn't bother to stay in the closet, succeeded, and thrived in this tough world.
Twitter insists that the day is just around the corner that companies will want to spend millions in advertising on the site, but Twitter's commitment is still prioritizing users over a desire to quickly generate cash revenue.
Brands are ditching advertising, which is really pretty transparent in its intentions, in favor of spin and PR, which really is not. This shift is partly because advertising is failing and partly because PR is right for the times.