The more your company relies on technology, the more problematic IT disasters are for your company. Being proactive with IT security and maintenance reduces your chance of IT problems. However, even the best security and maintenance will not eliminate all problems.
So, you need to be prepared for issues like power outages and denial of service attacks. Because the difference between whether an IT issue is a problem (e.g. ransomware forces you to use a backup from the day before) or a complete meltdown (e.g. permanent loss of critical customer data) comes down to proactive planning of disaster and recovery plans for different scenarios.
When done properly, a disaster and recovery plan includes different scenarios and a clear plan of how to handle it if something does happen.