"Best practices" aren't enforceable rules. They're simply guidelines businesses commonly follow in one area or another. If you're in retail, for example, one best practice might be to always ask customers checking out if they found everything they were looking for. This serves two purposes: It conveys a feeling of concern for the customer's shopping experience, and it may also lead to increased sales.
QuickBooks Online has many best practices, some of which may serve multiple purposes, including these:
They keep your company data safe and clean.
They provide insight on your financial status.
They save time.
They can lead you to better relationships with customers and vendors.