Maybe I'm missing something, because I'm in Europe, but AirBnB is mainly for holiday or business travel rental and so there are 2 caveats I personally find in your argument:

1/ Business: for my last travels to London, I looked at AirBnB, the up-front price was interesting, but after adding in the fees (cleaning and commission), it turned out to be cheaper to stay in a nice hotel. No surprises, clean room and breakfast included, right in the area of London where I needed to be. No going to suburbs for this.

2/ Holidays: why on earth would I want to stay in shabby flat in the outskirts rented out by "poor people" as you call them. That doesn't sound like holiday fun to me...?