What's bad for cities is not building enough housing for people who want to be there. That includes people who want to be there for a short time. Airbnb is bad for some city stakeholders, but good for other ones (e.g. people who want to rent out their apartment while they're away on vacation).

That assumes you have an infinite city. However, unless you want to destroy the historical center of the city with skyscrapers, you do not have unlimited space for the housing to grow.