>They benefit their customers
While making it a nuisance for people actually living in the city. I live in a condo in downtown Toronto, and every tenant in my building unanimously hates airbnb residents. There are weekends when people who airbnb and come for the sole reason to party throw liquor bottles and garbage in the lobby, destroy elevator buttons because they can't access their floor with the fob, puke in the hallway/elevator when they come back from a night out at 3am. The list goes on. While it definitely does benefit people who actually want to travel and are respectful of the building, not everyone is like that.
>their hosts (many of whom keep their finances afloat through AirBnB revenue, or have been able to enjoy life-changing increases in their standard of living
Agreed, but this is when Airbnb is actually used how it is supposed to. Either the host lists it as a short term rental for a one off weekend, or a spare bedroom in their apartment. What ends up happening for a majority of units is, that a lot of rich people end up 1+xth property just for the sole reason of Airbnbing it full time and thus decreasing the supply of long term rental units for people in the city. You know what this leads to.
If airbnb actually cared, they would have more checks before a host can sign up, work the city to give them names of owners who list their unit for more than allowed days (a lot of European cities actually allow 90 days of rental or something similar), work with condo-boards to ban the building if it's against the building policy, etc.