Houston is not a free-for-all. It requires a minimum number of parking spaces for different uses, which encourages sprawl. Its complex development code limits how many homes you may build on an acre. But it has no zoning, and its density restrictions are less severe than in almost any other large city.
The surprisingly strong argument for abolishing zoning is the rare case of successfully moving the “Overton window.” It should make all of us more sympathetic to fundamental reforms.