It's not that they accomplish nothing at all, but what they accomplished was evil. From my studies and reading^1^, I think that zoning law started out with good intentions to keep noxious industry (tanneries, blacksmith shops, livestock, etc.) away from dwelling places. Like so many things in the United States, though, it quickly got co-opted for racism.^2^ The Supreme Court issued a decision barring housing discrimination, so the Federal, state, and local governments turned to zoning laws to keep Black people out of white neighborhoods by, e.g. mandating minimum lot sizes, and construction methods, that priced suburban houses out of reach for Black families. Nowadays, we have this pervasive myth that such restrictions were to foster a rural aesthetic, for environmental preservation, or the result of auto industry lobbying, and those probably contributed, but the root of it was segregation. This becomes clear when you learn about what happened when some Black families succeeded financially anyway, and tried to move into white neighborhoods, like the Cicero, IL race riot of 1951.

1. Zoned in the USA by Sonia Hirt is a dry, but good read for a super-nerd, as it compares Euclidean zoning in the U.S. to land-use laws in Europe.
2. The Color of Law: A Forgotten History of How Our Government Segregated America by Richard Rothstein blew my mind with evidence of just how deliberate and explicit it was.