I agree with you that the best thing to do is to relax the regulations for building (and permitting, etc etc). I was talking about fallbacks when building is not an option (either politically or because of a labor shortage or otherwise).

"New York University economics Professor Edward Wolff, a specialist in real estate statistics, said 4.48 percent of American households owned three or more residential properties in 1998, compared with fewer than 1 percent in the early '90s."

I wonder what that number is today...