Microsoft 365 allows you to provide user within your organization custom made templates for Word, Excel and Powerpoint. 
This requires you to create or use and existing Sharepoint page and within that one or multiple document libraries need to be designated to store the templates. 

This can be useful if you want to give other departments the ability to manage it easily and not going through the hassle of applying the templates through scripting by copying the templates into a specific folder.

I use PowerBI primarly with CRM Dynamics 365. I just like the multitude of options it gives you in creating reports and graphs for users compared to the out of the box functionality in CRM Dynamics.
There's even a build in integration, so it's like Microsoft is practically begging me to use it.

I make a lot of reports that contain weeknumbers, like for example the amount of activities completed for each week. However PowerBI doesn't care where you are from, by default it applies the US definition of how weeknumbers are defined.
I'm from the EU, where ISO 8601 is being used and because of this alot of my users report that their activities are in the wrong week.

Sometimes a retention policy isn't enough, can't use it or you simply just need to run it once in your lifetime. 

To be honest, there isn't much reason to use this. The Microsoft Admin portal has an simple export button that does the same thing.
I only made this because at the time I didn't have access to the admin portal because it was managed by another department and I needed to see who has a Office license.