Not everyone is mortgaged - quite a lot of the price rises are driven by foreign capital flight. A few places have figured this out and decided to tax it: https://www.bloomberg.com/news/articles/2018-02-20/british-c...
I'd love to see a retrospective analysis on Vancouver's protective measures to see if they did actually help, or if buyers found loopholes, or it wasn't Chinese buyers to begin with.
It brought in some extra money to Vancouver though.
I would say that at this early stage it looks like the new taxes are working precisely as intended.
https://smartasset.com/mortgage/what-is-the-typical-down-pay...