California has millions of dry, dead trees owing to a bark beetle infestation and multiple, 100-degree+ heat waves. Do you know how hot that wood burns? More than a few trees together, and it burns hot enough to spontaneously combust trees up to a few dozen feet away.
Without wind. California's forests are
dense. They're dense enough that fires, even controlled burns, can and have generate firestorms--where the heat of the fire generates its own atmospheric wind system that feeds the fire.
Do you know what sort of embers these sorts of fires generate? The kind that fly hundreds of feet, retaining enough heat to light structures on fire when they land. Take a look at the shots of the Malibu portion of the Hill/Woolsey fire: there are structures that burned almost a quarter of a mile away from the closest flora.
So the reason that California cut back on controlled burns? Because due to the factors described above, controlled burns very quickly become massive, uncontrolled conflagrations. Controlled burns are something you can do when the trees and climate is relatively wet, since only the stuff you set on fire burns, or where flora is far enough apart and weather patterns mild enough that the fire can't spread on its own.
But you know what's really unbelievable? Someone who doesn't know diddly squat about what they're talking about who thinks they know better than the people who actually have to deal with this on a regular basis.