Actually, I think it grew out of the de facto "ad campaign" we've been subjected to for decades by the "arts crowd's" ugly sister (i.e. mainstream media).
You are definately right about the pro-gay “ad campaign” that we have all been subjected to for some 20 to 30 years. I was switching channels on my tv when I caught a minute of a sitcom. There was a young girl about 11 who was teaching her parents about gayness. It was very heavy handed propaganda and not funny at all. This reminded me why I stopped watching ABC, CBS and NBC years and years ago.