True in much of Silicon Valley (especially places like Palo Alto, which want to retain a suburban layout), but there's some moderate densification going on in San Jose. It lulled for a bit during the financial crisis because a bunch of projects' financing fell through—some apartments under construction had work stopped for ~2 years. But construction seems to be back in swing again now.
The dominant political view in the area is that building high-rise anything anywhere is something that should be stopped at all costs