@Peter1
In the UK, if a flight is seriously delayed, which means several hours, let alone a whole day, and the airline is at fault (technical issues, underbooking etc) rather than it being due to reasons outside of their control (weather, security risks etc), it is actually the airline's responsibility to provide the passenger with essentials, which can include accommodation, and also often compensation.
You can find the different circumstances that apply here: https://www.citizensadvice.org.uk/consumer/holiday-cancellations-and-compensation/if-your-flights-de...
Now of course, this will vary from country to country, but it's worth looking into. For example, I remember once when I was in Bangkok a few years ago and my flight was delayed due to technical issues, the airline put the passengers up in a super fancy 5* + hotel. Although they managed to put us on another flight that night (I never got to sleep in that insanely glamorous suite they put me in), once the delay was more than a certain number of hours, they still had to book a hotel rather than make us wait in the airport.
So, guests may have another recourse even if they didn't take out travel insurance. At the end of the day though, it's really not the host's responsibility to reimburse guests for unspent nights outside of the cancellation policy and the stated extenuating circumstances. The listing was ready and waiting for them and it's not like you could have rebooked it, whereas they could have taken out travel insurance.