Restrictions on housing expansion are generally very local, with projects being blocked on the municipal level, or on the neighborhood level. But actually, more housing in a neighborhood would tend to benefit homeowners there. As the neighborhood becomes denser, rents might go down, but land values will go up, since a given piece of land can now be used to build a more profitable apartment building.
What is really blocking housing is simply aesthetics, misguided economic and political beliefs, and fear of change.