Microsoft 356 Business is used across my entire organization. Some people are power users, others don't realize the power in Microsoft 365 Business. Because Microsoft 365 Business comes with desktop versions of Word, Excel, and Outlook, some people don't realize they have access to the whole suite of programs online.
Much of the day to day business functions our offices does is in Microsoft 365 Business. In my department we use it for email (Outlook), writing proposals (Word), and budgeting (Excel). Many in my department also use OneNote on a regular basis.
Throughout different departments, the suite is used for presentations, reporting and project/task management.