Yes, +1 to this feature request.
It is extremely limiting to have only 3 built-in User Groups and no ability to create custom user groups. In my case, I need to create at least 8-10 groups based on specific VLANs (and one based on specific MAC addresses if possible). This would help segregate VoIP traffic from guest wifi, home-office, printers, servers, admins, home users/adults and home users/minors. This would help me set different QoS and content blocking policies.
Allowing custom User Group creating based on VLANs, IPs, and MACs is an absolute necessity. I am extremely surprised that no one thought of this from the beginning. It just seems like a large architectural gap.