I agree but unfortunately in my experience the opposite is true in Texas - newer construction usually has thinner walls with less dampening between dwellings. Windows are usually fine though.
In Silicon Valley, sure, most of the housing stock was built rather a long time ago, yes, but it was also built to the expectations of people who didn't make a lot of money. The newer stuff around here is built for people who are in the top 5% or better of incomes, so it's likely they use more expensive construction techniques, too.