When only one thing goes down, it's easier to compensate with something else, even for people who are doing critical work but who can't fix IT problems themselves. It means there are ways the non-technical workforce can figure out to keep working, even if the organization doesn't have on-site IT.

Also, if you need to switchover to backup systems for everything at once, then either the backup has to be the same for everything and very easily implementable remotely - which to me seems unlikely for specialty systems, like hospital systems, or for the old tech that so many organizations still rely on (and remember the CrowdStrike BSODs that had to be fixed individually and in person and so took forever to fix?) - or you're gonna need a LOT of well-trained IT people, paid to be on standby constantly, if you want to fix the problems quickly, on account of they can't be everywhere at once.

If the problems are more spread out over time, then you don't need to have quite so many IT people constantly on standby. Saves a lot of $$$, I'd think.

And if problems are smaller and more spread out over time, then an organization can learn how to deal with them regularly, as opposed to potentially beginning to feel and behave as though the problem will never actually happen. And if they DO fuck up their preparedness/response, the consequences are likely less severe.