I don't think that's really true as a blanket statement. I stayed in what turned out to be a depressing, small, rental apartment in Denver for a weekend via airbnb, because it was something like $20/night. The place smelled like trash and there was no laundry on-site.

You might say that any type of travel is a luxury. Ok, I guess. This trip was for a funeral. The flight was under $100. While I'm fortunate to be able to afford such a thing, no part of the trip was "luxury travel".

Airbnb serves a wide variety of customers, via a large range of temporary housing options.