I'd have to disagree, or at least advise caution.
Sending messages from the LMS to a students social network can backfire, and it needs to be handled carefully.
Anyone considering something like this needs to take into account why the students are using the social network, whether it be Whatsapp, Facebook, Twitter, Ello, whatever.
If the users aren't receptive to messages coming from their lecturer, teacher or institution, then at best they will ignore it. At worst they'll be upset and be less inclined to engage with you.
My point is that while it may be very easy to do, or in the case of Whatsapp difficult to do, the needs and receptiveness of the students using the social network need to be taken into account.
It isn't that dissimilar to "brands" trying to engage users on social media. When was the last time you were receptive to an advertisement appearing in your twitter stream?
Just a thought