It goes back at least as far as the 80s. As I was completing my BA in History, a professor asked me what I planned to do. I said I was considering going on to grad school and then teaching. He stopped me right there and told me flat out that I’d never be hired because my politics were wrong.
I should clarify — my politics were “wrong” in the context of “not what they would be looking for”. The professor was not indicating personal disagreement with my politics (although he did disagree with my politics).
For my take on "Diversity:" Diversity In Context.
I had a similar experience in the early 70s, in grad school. I was in a ‘community/junior college teaching’ program.
One day in class, the prof spanned the classroom of about 25 grad students and stated that the black females (2 in class) would have no problem getting jobs when they graduated. The black males (3) would also find jobs, especially in physical ed and arts/humanities. The remaining females (15 or so) would likely also find welcoming arms when job searching.
As for the 5 of so non-black males (included me), we would find it very difficult to find jobs less we were in a very specialized field.
I recalled sending applications to community/junior colleges from Alaska to Florida and California to New Hampsire. I got a total 3 interviews and no job offers.