The problem with enacting any kind of federal housing policy is that it affects the entire country, not just Ontario or BC. Pretty much every other housing market in the country is balanced or slow, so people buying in the majority of the country aren't tripping over themselves to buy something before prices shoot up again.

Slowing the market in two provinces might sound great to people who want to buy there, but it'll mean that the people who don't qualify for the properties they want will either not buy or buy less expensive properties, squeezing the people below them off the property ladder completely. 

Looking at the other comments here, is it mandatory to say something ideologically-driven and irrelevant before finishing my post?