Indeed. But my argument is specifically that the norms around acceptable behaviour for a straight male have significantly narrowed from roughly the end of the 19th century to the 1960s.

I'd argue that the trend continued past the 1960s. While yes, there is certainly more acceptance of homosexual men, there is also a continuing trend towards an exaggerated extreme masculinity that would have felt out of place in the 1960s.

Maybe it's more accurate to say Western (and in particular American) culture has fragmented, and one of those cultures has increasingly put stricter and stricter norms around acceptable heterosexual male behaviour to the point where it's nearly parody.