What is the concept of Microsoft account? What is the benefit to the user?

Able to download, install and restore applications from the windows Store

In Dynamics CRM customer records are classified into two types Accounts and Contact. Accounts is for tracking B2B relationship with customers like organizations, business entities, firms, etc....

So you will find out of the box fields and features inside the account entity designed to work in this context. 

1. enables users to log in to Microsoft services such as Office 365, Skype, Gmail,Outlook, Xbox Live, OneDrive and the Windows online store with the same username and password combine in one time user.
2. Designed to one time log-in with different account registered.

The most obvious benefits of using a Microsoft account include the ability to download, install and restore modern UWP apps from the Windows Store. If you have other Microsoft devices, like a Windows Smartphone or an Xbox, then a Microsoft account would help you access unified apps and games

Using a Microsoft account include the ability to download, install and restore applications from the Windows Store.