RBAC, Group and Role without Assignment

hi all,

is it posible to use a RBAC Group with Role without a Assignment?

I think in this example we don't need the second and third Line if we add ApplicationImpersonation Role to the new-RoleGroup NetbackupRoles?

 New-RoleGroup -Name NetBackupRoles -Roles @("Database Copies", "Databases", "Exchange Servers", "Monitoring", "Mail Recipient Creation", "Mail Recipients", "Recipient Policies")
 Add-RoleGroupMember -Identity NetBackupRoles -Member NetBackupUser

 New-ManagementRole -Name SymantecEWSImpersonationRole -Parent ApplicationImpersonation
 
 New-ManagementRoleAssignment -Role SymantecEWSImpersonationRole -User NetBackupUser -Name "NetBackup-EWSImpersonation"

Chris