I find it interesting to that people don't use WhatsApp at all. Many posts here are claiming not using WhatsApp is impossible. Grandparent's experience demonstrate that it is.
That's an unbelievably poorly colored map -- 3 subtly different shades of green, 3 subtly different shades of blue. It's almost as though a colorblind designer set out to make everyone else suffer.
This heavily depends on country of residence. While I had been living in Serbia, there was one king - Viber. I've heard of WhatsApp back then but didn't know a single person using it. In Germany it's vice versa - the king is WhatsApp, nobody heard of Viber.
It's not that surprising. If you live in the US and don't need to text people in other countries, you probably can avoid WhatsApp pretty easily, but it's pretty much the defacto option for texting non-US family and friends, and in many countries it's the predominant form of mass communication.
UK here, have never and will never use any fcbook property and didn't use Whatsapp before then. For me it's Signal, Matrix or folk can SMS me to give up their privacy without pushing me into using other services to do so.
I have a dedicated device for wechat. I recently put whatsapp on it (with a burner phone number) because my parents refuse to use anything else and would attempt to reach me via nearby people who happen to have whatsapp. I will likely remove it again rather when it forces me to "consent" to data sharing. I am extremely uncomfortable with whatsapp, much more so than wechat even.
Canada here, have used WhatsApp perhaps 5 times, all just to communicate with small teams at events. Always uninstalled it right after and honestly have never A. missed it, or B. been asked why I'm not using it.
Most Americans, for example, have no need for it. I feel like iMessage is the dominant messaging platform in the U.S.