You don't understand that for us Whatsapp is as important as one of those functions. You wouldn't buy a phone that doesn't offer calls just because many people use one or the other VoIP app.
We want the one thing we can reach everybody with, not check all the alternatives and hope the other person might use one of them.
Whatsapp is the only messenger I have installed. I tested most of the other ones, however with only 2 or 3 of my contacts using them, I didn't see a reason to keep them.
Yes, Whatsapp is that big in Europe.