Except this still will not help due to the economic forces driving urbanization. Silicon Valley is a self-fulfilling prophecy and creating more supply will only help to drive more demand.

Every new person newly moving into a heavily urbanized area will drive 0.5 more persons wanting to go there due to new network and auxiliary jobs created (groceries, haircutter, ...). As more than 70% of our jobs are by now defined by interactions with other people, urban centers of excellence are doomed to grow.

This is why building new housing is only ever a short-term solution as well. The only long-term solution to urbanization and gentrification is making these areas less attractive by offering less jobs in a major area.