Now you are realizing why some of us have chosen to exit the Windows support field. ;-)

Always remember that Microsoft is an enterprise focused company. Their number one cash cow is Windows and Office, mostly from licenses to businesses and enterprises. For your current situation, Microsoft expects and has written all of their networking code around the idea of a domain server being in place and managing all of this. Making file sharing work in a home, or an environment without a domain controller is a lower priority from a financial stand point. It's sadly not surprising there are issues like this.