That's quite a broad assumption based on anecdotal evidence, you know what's true based on your few experiences renting and from a few listings your immediate family has, how can you even believe it's true based on this flimsy data?
Quick edit: just searched on both VRBO and Airbnb for rentals in my city for the same date range, VRBO shows me 191 options, Airbnb shows 330 options.