Microsoft backs up your data right? So who needs backups? The answer to this question is everyone. Microsoft does backup your email, the problem is they only retain that backup for 30 days. After 30 days the data is permanently deleted. While you might not see this as a major issue today, it could become a major issue in the future. Let’s say you have a lawsuit filed against you for the actions of an employee and you have already fired the employee. Once the employee is fired and their M365 license is remove the clock starts ticking. If you had a backup solution in place you wouldn’t have to worry about having the data.
The second point I want to make is that Microsoft only backs up Sharepoint every 12 hours and those backup are also only retained for 30 days. Guess what also resides on the Sharepoint infrastructure. Teams and One Drive use Sharepoint as their backend storage. Could your business afford to lose an entire days worth of work? With a backup solution in place you wouldn’t have to worry about this situation ether.