Exactly. In all the discussion of this by normies, there seems to be this idea that backups are an instant-restoration-of-service wildcard that can be deployed at any time.
A full backup system will take hours, sometimes even days to be fully deployed - especially when there are many interdependent systems affected. And, in case anyone hasn't thought it through that far...as soon as they completed the build procedure, including ensuring that all the security software was up to date, they would reboot and it would instantly show the same problem again (prior to the discovery of the actual cause of the issue).
Backups are not a silver bullet for configuration issues. They're a last resort for data loss, which was not the issue here.
Now, a hot spare...that's something that could potentially have been useful, if every company involved had a hot spare of their entire infrastructure...but again, that would've also been affected, because the security software would necessarily have to be kept up to date.