And Silicon Valley is uniquely messed up by Prop 13 and NIMBYs, not to mention the fact that there is no room to sprawl out like midwest cities given the geography.

That's not to say that other cities don't have a similar mix, but those other cities are not home to the headquarters of highly-paid software folks who all compete for housing. Even Seattle folks priced out can possibly afford places way up north in Everett or down south in Tacoma, if one absolutely must have a house for whatever reason. Even cities that are a heinous commute to Silicon Valley (e.g. Santa Cruz) are still wildly expensive.