Because the commies McCarthy warned us about took over not only Hollywood but also media and academia.
Yes. See my post above. I detest it when I see people I would tend to regard as allies use this asinine “Red Scare” trope.
As you accurately point out, we have reaped what was sowed. Joseph McCarthy should have been treated as an American hero, as he made Communism disreputable, and purchased us about 10-20 years, but we squandered that respite.