The latest WhatsApp beta has a new feature we have not noticed earlier.
WindowsUnited.de has discovered that it is now possible to extend group invites via a shared link, rather than having to invite each person individually.
This would for example let some-one post a link in a forum and have even strangers join the WhatsApp chat group, making them somewhat akin to Telegram chaels rather than simple group conversations.
WhatsApp beta is a closed beta, but the improvements should come to the mainstream version of the app in due course.