Backups are absolutely essential but I think you understate the amount of hours needed to restore an entire corporate network if it's compromised and encrypted at once. (As Colonial apparently found out)

I think the perpetrators are now taking data "hostage", and threatening to release it publically unless the ransom is paid - in this case backups don't help, though it depends on how sensitive your data is.

In any case, that type of attack wont disrupt the business (in the short term)

But first you have to figure out how you got owned the first time and fix the issue. Otherwise you'll just get owned the next day again...

And offline backups

And to add to that, offline backups that go back 90+ days. Ransomware gangs frequently use time bombs to deploy their encryption after sitting within a system for a month or two. If you get hit by one of those gangs and only keep backups for 45 days, you're screwed, because your backup is still infected.