This is true,I cannot purchase Apple Music because AFAIK, you can't selectively share subscription with a few family members. I have an active iCloud Storage Plan that I share with my wife. If I were to enable Apple Music and add other people to family, they will get access to iCloud Storage as well. I can disable iCloud Storage sharing with family, but that will mean even my wife won't be able to share the iCloud Storage with me. Someone please correct me if I am wrong.
This is why still no Apple Music or Apple One sharing group formed.
To share apple music - the owner of the group need to create new apple id and the other 5 person also agreed to do so.