1978 was a bad year not only because of the passage of Prop 13, but the subsequent municipal votes in SF and LA to force them into compliance with the statewide zoning restrictions of the Consistency Law. CEQA became weaponized and successfully used by NIMBYs to thwart new development.
However, specific to post-1978, municipalities saw residential areas as a tax burden and enacted growth caps and levied "impact" fees. This was a direct effect on housing development as governments did not want to bring in new residents without the property tax base to support infrastructure, education, etc. It wasn't just an inclination to support restrictive zoning, it mandated lowering density. Meanwhile commercial zoning flourished as commercial taxes became more relatively viable. As a result, LA now has 1 house for every 2-3 people, and nearly 2 parking spaces for every 1 person.
Zoning is a problem. I just think that maybe it wouldn't have turned out this way without Prop 13.