Because a lot of these houses sit there vacant for big percentages of the year. For example (easy numbers) if your mortgage is 1k/month, you can afford to rent it out for 200/night a leave it vacant the other 25 days of the month.

You ever see a hotel on a Tuesday? No one is there. Now stretch that across all the airbnbs in a city.

I don't understand how someone can't see how that isn't bad and is crating artificial scarcity. Homes are not hotels.

airbnb contributes to the problem but doesn't create it. It also makes for bad neighbourhoods.