This is a very interesting point and may very well explain the continued appreciation in values. But it only takes one law from the city to turn the tide. Just like in Vancouver where the city made AirBnB illegal, Toronto could do the same. In fact, it should do the same. When your local citizens who work in the city don't have a place to live, its a problem that politicians will need to solve.
I'm personally not comfortable with this whole AirBnB model and how it skirts the rules established for the hotel industry. Are these AirBnB hosts paying the hotel tax? Are they even paying their taxes to begin with? Once you equalize all this, maybe running your AirBnB isn't as lucrative, and worse, it might be illegal one day.
Where do you get your facts? Or do you make it up?
https://vancouver.ca/doing-business/short-term-rentals.aspx