Good IT security and proactive maintenance greatly reduce IT problems. However, even the best security and maintenance will not eliminate all problems. And the difference between whether something is a problem (e.g. loss of data that takes an hour to recover) or a disaster (e.g. permanent loss of critical data) can be whether your IT team has created disaster and recovery plans for different scenarios.
Disaster and recovery plans allow your IT team to look at different scenarios and put some backup options in place before a problem strikes and to have a clear plan of how to handle it if something does happen.