That is to say, media and academia aren’t leaning ever further left because a bunch of lefties got into a room and decided to oust the conservatives. Mostly it happened because human beings tend to think that others who agree with them must be especially fine people. That “affinity bias” influences hiring decisions, often unconsciously. The fewer conservatives there were, the more pronounced the skew came, a process that sped up as it advanced.
Now, of course, there is a muscular young generation that is explicit about wanting to “cancel” conservatism. But that’s a new phenomenon, and the tilt is decades old. If anything, the causation is reversed: Only when almost all the conservatives were gone did it became feasible to say that universities, magazines, awards ceremonies and the like should be explicitly left-wing projects. And if they do succeed, the skew will become self-maintaining; no one will voice a commitment not to hire conservatives, because conservatives won’t apply to places they see as hostile to their interests, their ideas, their selves.
If you understand how those institutions could arrive at a stable, no-conservatives equilibrium even without overt hostile action, then you understand part of the social dynamics behind systemic racism. The way small decisions cascade into major social forces is how Americans who profess no racial hatred — and declare their implacable hatred for racism in all forms — could nonetheless end up contributing to patterns of residential, educational and employment segregation that left the average black American with fewer opportunities for well-paid office work than the average white person.