Mentors don't always think about pinging newcomers, or they do it the wrong way (after sending the message, which may not always trigger the notification).
Since we rely on this notification (we say that a notification will be received), a solution that makes pings happening for sure should be implemented. Newcomers are expecting to have a ping, since the popup tells them they will receive one:
Source for the discussion: https://www.mediawiki.org/w/index.php?title=Topic:W1goooycq8ddppg1