The few authorities who do permit ten women to use the "zimmun be-Shem" formulation explain the necessity for ten in this case is unique and cannot be compared to other instances requiring "minyan".
The few authorities who do permit ten women to use the "zimmun be-Shem" formulation would not extend this permission very far. They explain the necessity of needing ten in this case is unique and cannot be compared to other instances requiring "minyan".