Terrible tragedy. I can definitely see the argument that Airbnb hosts should carry insurance for freak accidents / deaths that occur on their property in cases like this.
I.e. If you try to buy a car they warn you about possible scams before you can look at the listings. Airbnb certainly does not do enough to proactively warn potential guests that they cannot vet the safety of any unit listed on their website.
I think it's just a tragic accident, yes it could have been prevented, but what accident couldn't be? There are risks everywhere, and trying to remove them all isn't possible or efficient. We go after the low hanging fruit because it saves more lives. If this were carbon monoxide poisoning or a fire (with no smoke detector) I'd be with you blaming the property owners - but this wasn't something they should/could have prevented.
You grew up in the city, right?