I'm probably missing something very basic, but for the life of me I can't see why Ransomware is such a problem.

Yes, it's a pain. Yes it leads to the loss of several hours of time, etc, etc, etc.

But why is it a problem that a good daily backup can't fix effortlessly? What's wrong with a quick disk-wipe and restore from backup? Then it's back to work and there's no need at all to put your hand in your pocket for thousands/millions in ransom, and being 'offline' until the hackers come good on their promises to fix your data?