Let's assume an account synced on multiple devices. In example, a customerservice account used by 3 employee There are multiple contacts to handle, but the company is divided in geographic zone, so user1 is for zone1, user2 is for zone2 and so on.
Grouping contacs in groups (but all users should be able to see all groups), would be useful to make things easier: if you have to follow the zone2, you just check for zone2 messages.
without the grouping, when you receive a message from a customer you have to check if that customer is under your zone or not.
In this way, you can also shut up notifications coming from a different group than yours. Something similiar to a Telegram group
I'm not sure if this is clear. I hope so.