custom tab-app authentication

Thanks  Varaprasad-MSFT   for your clarification.  Appreciate your perfect answer.

As a follow up I have one point to clarify between  2 types of custom-tabs i.e.,  static tab and configuration tab-authentication . 

As long as we are talking about the static-tabs  I am totally onboard with the  diagram at https://docs.microsoft.com/en-us/microsoftteams/platform/tabs/how-to/authentication/auth-flow-tab 

My understanding is the same diagram flow can be triggered and accomplished by the "configurable tab"
So, if I put it hands-on way,

let's say there are 3 members on one channel where this configurable tab-app is installed.
All 3 members will go through this authentication-flow, consent all the scopes required by the tab on their MS-teams client.
Now, this tab will have OAuth token for all 3 members.
So if the job of this tab-app was to show the latest 5 emails then would the output-UI on the tab screen would be different for all the 3 members  ??
That is not matching with my understanding because as far as I know, the "configurable tab" should provide information that is common and helpful to an entire team.
There is no member specific information. So what was the use of delegated-OAuth token ?

Should not configurable tab be dealing with only  Client-credential authentication flow and get the app-level token using its own client-id/client-secret ?

If it was static-tab, I would totally understand the importance of sign-in.

Appreciate your help.

Thanks.