Old Urbanist has a thoughtful retrospective on single-family zoning that’s worth reading.
It’s worth noting that from its inception it was obvious that exclusionary zoning practices were designed to do just that: exclude and segregate. From Euclid vs. Ambler (decided 1926):
The plain truth is that the true object of the ordinance in question is to place all property in a strait-jacket. The purpose is really to regulate the mode of living of persons who may hereafter inhabit it. In the last analysis, the result to be accomplished is to classify the population and segregate them according to their income or situation in life (297 F 307, 318 ND Ohio 1924, 272 US 365 1926).