Airbnb is evil, because it facilitates and profits from rule and lawbreaking, up to and including turning whole apartment buildings into pirate hotels, while spinning the tale that it's all about individuals occasionally renting out their primary place of residence for a couple of days. It's evil because while occasional random temporary sublets aren't a problem, they become a problem when they stop being random and instead become a coordinated, frequent phenomenon.
It's evil because its whole business model is making money by encouraging people to break social contract and do wrong against their neighbors.
Sure, hotels, motels, hostels, and all other legit accomodations aren't perfect. But this isn't the way to fix them.