I believe that when a group is formed on WhatsApp it does increase communication ability between the persons in the group. A group formed on that platform is normally people that are personally known to each other such as family or friends.
With people living busy lives personally meeting/visiting can be can be difficult to arrange and therefore infrequent. However, in forming a WhatsApp group the foregoing can easily be overcome and frequent chats and a get together online can be entertaining and full of news updates.
WhatsApp is far different from Facebook or Twitter I find due to the group's personally knowing one another and therefore making a far different online atmosphere.
That stated, I am not a user of Twitter or Facebook these days, but a member of three WhatsApp groups being, family, a group of longtime friends, and a group my wife and I go walking with
WhatsApp enables us all to keep in touch easily and frequently