There's rules and regulations against it, for one. Should locals be allowed to do whatever they want on their property with no regards to how it will impact neighbours and local economy? There's a reason we have zoning laws, etc, in place. There's lots of things we stop locals from doing because it's for the better of the community as a whole, and renting out short-term to tourists should be one (and, again, it sometimes already is but AirBnB allows them to skirt the regulations).