Citation needed, my understanding was that housing prices are being driven up by real estate owners/agencies buying tons of property to either rent at extortionary prices or sit on until they sell for a higher price to the next sucker. Also stuff like the RealPage scandal where they simply illegally collude: https://news.ycombinator.com/item?id=41330007

I think the idea of a law that only allows a limited number of owned properties per person and requires them to actually be using those properties would be interesting to alleviate this.