Humans have the technology to build structures that can withstand wildfires. It's like saying we should not live in cold climates before we had good insulation. I can build a concrete or metal structure that would be fine in a wildfire. Mountains have access to tons of water during the winter. They just need to retain that water for wildfire season.
Since you're a software engineer in SF, I wouldn't be surprised if you have the financial ability to pay a homebuilder to build a concrete home in a rural, high-risk area.
But even putting the costs aside (which are out of the reach of many/most California rural homeowners) do you have the ability (expertise, materials, LABOR) to demolish and rebuild thousands upon thousands of homes scattered throughout California?
It's simply not as easy as having the "technology" and snapping your fingers. Forget building houses. Even finding someone to drill a well for you on short notice these days is next to impossible.
