I don't necessarily disagree with this. To be honest, the way the housing market works sort of goes over my head, so I'm more than willing to just say that I'll take your word for it and that this is a valid concern.
Airbnb, for me, has just been useful. As I said in another comment, I live in England at the moment. This is only a temporary arrangement for me (I've been here two years and will be here a few more). I'm American, so I'm not used to being able to travel so easily from country to country. I love it. So I am trying to see as much as possible, which means I obviously try to save money as much as possible. I plan a lot of short trips, loaded with sight seeing, and on these trips, Airbnb has proved invaluable to me. I recently went to Iceland, and that trip was a bit longer and expensive. I went all out for that one and booked through an agency and stayed in hotels. so, it obviously depends what kind of trip I am looking at, but I've really grown to appreciate what Airbnb offers.
With all that being said, you make a valid point and I don't see why they couldn't make some restrictions if it were actually causing issues with the housing market.