Uploading your data to the cloud is like taking money to a bank: the data is yours, but up to a point! So, it’s important to have a copy of your business data at another provider and data center as well. Thinking that the Microsoft 365 cloud backup service is sufficient is wrong.
If you have a problem with a provider, so that you are protected, having a copy elsewhere is always good practice. For example, there may be legal and compliance reasons why the provider may suspend access to the data, without you having the opportunity for a quick resolution. Therefore, having access to a copy of your data is strategic.
In addition, if a migration were to become necessary, it would be difficult to export large amounts of data.