Well, they don't _have_ to rent long-term but if the unit is kept unoccupied, then they will be hit with the Empty Homes Tax in Vancouver, for instance. So yeah, they are forcing the landlords hand here.
And yes, I agree the house problem is a supply-vs-demand issue. And this is not addressing the core problem. But in a place with extremely low rent vacancy [2], having units removed from the market for STR isn't helping.
The empty homes tax is a joke. It's too easy to bypass (just have somebody you know use it as their primary address and add a few lamps on timers) and priced too low (in many cases the tax is cheaper than the costs of having long term tenants).