By extension, they also help to protect your friends and family, and the companies you deal with online.
Passwords help to protect you and your work. It’s not sensible to operate computers without passwords, and there is a strong case for making them compulsory. However, the whole issue of Windows 10 accounts and passwords is so important that it’s worth a longer discussion.
Asking Cortana for “change sign-in requirements” or typing req in the search box will get you to the right place. The quick and easy answer is to go to the Settings page of your account, look for the words “Require sign-in” and change the option to “Never”.