WhatsApp is taking a page from Telegram’s playbook by introducing a sort of ‘Broadcast Mode’ for groups. The idea is that group admins will be able to turn on an option where they are the only ones able to post; making it more like a channel for updates, instead of discussion.
This “Only Admins” option is intended to be used for pushing notifications; allowing the admins to keep a one-way flow of information in the group. Ideally being aimed at admins from news agencies, schools, corporate communications, or public interest groups. In essence, anyone who needs to tell a large group of people things from time to time.
Telegram was the first to introduce the idea of using channels to broadcast information, with the system designed to protect the anonymity of those subscribed. WhatsApp, in this respect, is less useful for large groups of strangers as it still shows the phone numbers of everyone that joined.
Still, it’s useful for small groups that need to be updated on things without providing feedback. Or as a secondary channel for keeping people updated without information being lost in the chat.