In my experience, Airbnb's biggest competitor is HostelHero and I found this much more convenient than Airbnb while traveling (if only because hostels nearly always have space, unlike the many rooms we encountered on Airbnb advertised as free but suddenly not when you book them).

Arriving in a new city without internet it was great to have HH and be able to find 10 hostels and know they are going to be open. I guess McDonalds wifi etc. means Airbnb could have been a competitor, but the ease of finding accommodation reliably, of a reliable standard, and at more affordable prices meant we used HH far more than Airbnb.

Having said that, the times we could manage to find a room that was genuinely free, and appeared to be genuine people with a spare room, were some of the highlights of our travels. The people and the rooms were both fantastic, and it's this "home away from home" and social aspect I think Airbnb should be pushing. I think at the same time they should be working hard to remove the listings that I could best describe as dodgy guys trying to run a hotel out of an apartment building without adhering to local hotelier laws as we found these far too prevalent in some cities.