Correction: zoning had good reasons to exist, but it doesn't anymore. Everything that we used to solve that problem is better solved by environmental laws than it ever was by zoning. It turns out that if you make companies pay for their environmental pollution via noise, chemicals, air pollution, etc., they tend to locate their industrial capacity where it is easier to solve or less impactful.

And while every single reasonable but outdated justification for zoning has slowly disappeared, zoning has been thoroughly co-opted by greedy sociopaths and meddlesome wannabe HOA presidents who want to control their neighbors and police aesthetics and keep out undesirables and inflate the value of their investments.