I doubt these factors are statistically independent -- the most popular neighborhoods for tourists and yuppies have always seen prices grow faster relative to the overall metro, and more popular/high-growth/expensive neighborhoods will naturally attract more Airbnb hosts to take advantage of their location.
In any case, assuming people travel the same amount, it is zero-sum (Airbnb saved NYC visitors 616 million dollars and also transferred some percentage of tourism income from hotels to a broader collection of residents). However, I think Airbnb enables people to travel more (I certainly travel more with the incentives of cheap, reliable Airbnb lodging), so we need more data to determine whether the lower prices actually incentivize a sufficiently high increase in tourism to be a net positive for tourist-mecca economies.
Even if it comes out to a net negative to tourism-based economies and it increases costs for local residents, I'm curious what the Airbnb witch-hunt crowd is proposing. Limit tourism / make it harder and more expensive to travel? Reinstate the hotel cartels?