By default, Windows 10 prompts you to create and use a Microsoft account even if you are just planning t use the operating system's local services only. From a security point of view, not using a Microsoft account can help you keep all your information and activity almost completely local to your computer.
There are significant advantages with the use of a Microsoft account from a functionality point of view. Pulling in your Outlook email or files from your OneDrive account are tasks that become easy, as such functionality can be fully integrated into your OS experience.
However, from a security point of view, by using a Microsoft account you are providing the programs and services at the backend a way to put together a big picture of all that you are doing day in and day out. So, the convenience comes at a price, and it can be very high sometimes.