Airbnb guests are no more 'random' to me than any other non-fee-paying guests-of-my-neighbors who are in the building from time to time.

Perhaps Airbnb guests are less random, given the sticky reputations, payment/identity auditability, and commercial guarantees/incentives.

For example, outside of Airbnb, a neighbor might feel a loyalty obligation to let some sketchy down-on-his-luck friend/relative stay over. In such a case there'd be minimal third-party recourse if this guest causes problems. (Provided the guest is legal under the lease, I don't think you'd have any case, against the host, for the guest's errors/crimes. You'd have to go after the guest, which could be a blood-from-a-stone errand.)

OTOH, when mediated by Airbnb, my neighbor-host can coldly avoid any particular Airbnb-guest by risk/reward calculations... and if the guest misbehaves then Airbnb's guarantees and reputation become additional avenues for remedy. That is, some factors make temporary (but accountable) commercial guests even less risky than other casual guests – and maybe even less-risky than some permanent residents!

There are plenty of hypothetical things that can go wrong, but we have to sum up the outcomes over all eventualities, under these new incentives, not just imagine worst-case scenarios. Let people flexibly work it out via contract, as we learn, rather than with blanket legislation.