A theory.

[Mint]

Eugene McCarthy is hardly a good example for the period you mentioned.  He was a crotchety old crank in a period that revolved around youth.

Not true, but to say Gene McCarthy embodies the "trend-left" of 1965-1980 is a little bizarre.

To say there was a substantial "left-trend" in 1965-1980 to begin with is bizarre. By the time Nixon got in we were starting to gut most of the great society other than those cushy middle class entitlements and there was a definite 'law and order' trend underway. Most historians call 1973 the end of the liberal consensus and for good reason.

[Mint]

...make colored people go to their own, underfunded schools?

No need, that's pretty much already the case.