I think you could already do that by using this in conjunction with the ‘Who can mention this group’ controls? For any group with over x amount of members you can have it as ‘Admin and Moderators only’, and then the @mention will display as eg @team, but no one will get a ping unless a staff member uses it.
(Fun forum fact: not even admin can ping @team on here now after I accidentally used it about 15 times in my first week… 
)