I see you are MSFT. Is this a customer question? Or are you facing this issue as a MS Employee on Microsoft's Yammer Network?
In the course of my work -
There are admins who insist for features that will push notifications to the users, regardless if they want it or not, and to prevent them from turning off that notification.
Then there are users who insist they want push notifications disabled, regardless if they are regarded by the sender as important or not.
Life is hard.
Here's my view -
"Announcements" in Yammer is an Admin feature. Announcements cannot be made by a regular user. If there is a overzealous admin, then this admin needs to be talked to, to achieve a balance between communicating too much or too little. If this is regarding
MS internal Yammer Network, and you feel you have a over zealous admin, then perhaps reach out to the designated community managers to give your feedback.
On All Company Group - Yammer best practices recommends teaching users not to post in the All Company Group. In an environment with a huge number of users, if everyone posts in the all company group then the message will get lost very fast. It is better
to post into the specifc interests groups where the audience is actually interested in the conversation.