That's just a blanket statement and doesn't apply to all airbnbs. My airbnbs are priced on the low end and are very affordable.
I have heard that airbnb prices are kinda crazy in USA though, and sometimes higher than hotel. Not sure about that...
My strategy would be to book hotel if the price is similar to hotel, and then book airbnb if the prices are significantly cheaper.
Edit: Just compared the prices for one of my rooms to a cheap hotel on expedia.ca. It's about like 1/3 of the price of a hotel room.