Here's one scenario. A family, with two kids, lives in a single family house in a neighborhood zoned for single families. A house on the block goes on the market.
Several families, with children around the same as the neighbors, tour and bid on the property. However, an enterprising person (who doesn't need the bedrooms for kids) uses the anticipated income from airbnb rentals (not to mention the absence of childcare costs) to outbid all those families. The SFR zoned house, on a SFR zoned block, is now a hotel, for all practical purposes. Guess the kids will have to find neighborhood friends somewhere else.
The visitors are quiet, polite. So, no harm no foul?
I understand that this scenario can occur in the absence of airbnb or even short term rentals(plenty of people rent out rooms in their houses), but there's an order of magnitude difference here. Also, I still see more benefit to this if these are permanent, long term rentals. They may be students who need a place to live, long term residents who need a place to live. I also think that unregulated and unresticted[1] airbnb makes this scenario much more likely (which is one reason why the company is so profitable, it has made it much easier to rent out "spare" bedrooms, creating a new market).
[1] properly regulated airbnb, which allows someone to rent out their house while they are on vacation, now and then, would not cause any of this harm.