I think this really depends on your industry.

If you cannot give a patient life saving dialysis because you don't have a backup generator then you are likely facing some liability. If you cannot give a patient life saving dialysis because your scheduling software is down because of a major outage at a third party and you have no local redundancy then you are in a similar situation. Obviously this depends on your jurisdiction and probably we are in different ones, but I feel confident that you want to live in a district where a hospital is reasonably responsible for such foreseeable disasters.