"The vast majority of the people who use [it] benefit from it" is true of many products that are correctly removed from the market because of the size of the minority that suffer and the scale of their injury -- weighed against the benefit to other users and society as a whole.

More importantly, though, the scope of the risk of airbnb is enormous and past performance is not a reliable indicator of future success. As these two examples of bad experiences have shown, the system can be gamed. As a larger and larger number of bad guys learn that this system can be gamed (and how) -- exploits as a percentage of use and percentage of value received (insofar as you can quantify that) will, it seems to me, almost certainly grow.