The purpose of most real estate is to provide shelter for people, not to sit empty and unused. That's exactly what AirBnb allows to those who are only willing to rent short term (because it's their vacation home and they want to be able to use it).
Housing someone provides a fundamentally different kind of value than offering a second home or short-term stay. A home meets an essential social need, while vacation homes and similar uses provide far less public benefit. On that scale, the social value of housing a person is vastly greater than the value of adding another short-term rental bed.
That does not mean hotels would stop being built, because developers and hotel operators are optimizing for a different kind of value. But it is more than enough reason to oppose turning even a single home into a de facto short-term hotel.
The reality is not simply that people are monetizing unused space. The ability to rent homes short term encourages people to buy more second homes than they otherwise would, because the income offsets the cost. It also encourages investment in housing that would otherwise remain in the long-term market, since owners know unused time can be monetized. Some buyers purchase properties specifically to operate them as Airbnbs, and many landlords convert homes that once served monthly or yearly tenants into short-term rentals because they can charge more, adjust rates freely, and often earn more overall.
You are referring to properties held by the already rich (only the rich can afford 'vacation homes').
If they can't afford a 'vacation home' without short term rentals then it should be sold and provide housing year-round and build equity for a new homeowner.