And the price to rent plumets when there is a glut of houses up for rent (via AirBNB or not). That this doesn't happen speaks more to the lack of supply than anything else.
Govenments have failed their constituents by not provisioning adequate land for new housing, and not buying up abandonned or severely run-down areas to redevelop.
Our populations have expanded greatly in the last decades, yet housing supply has not kept up at all!