Agreed, and my only use case for Whatsapp is a similar social group of colleagues (most of whom are friends IRL, too) spread around the world. This kind of platform was the easiest method of staying in touch, but in an unforced passive participation way. It works well.
I think this is true if you choose to make it that way, but for a lot of these, it really doesn't have to be that way. For example, I have a small (~10) number of friends on Snapchat; we generally share tiny tidbits of our life that we enjoy, and it helps us to know each other a little better in a manner that doesn't invoke jealousy.