HenryHoneyBalls and AdrianB: might be different in each country or for each generation, but I personnally don't know anybody using Whatsapp save for a few older people.
In any case, even if used (I totally trust you on that, as I said I might just not be in the right category), it doesn't affect my life in any way as everybody is on Telegram, and if not they at least have iMessage. Administrations use email (when they reply) and I've never heard of buying things on whatsapp or communicating with government services on whatsapp, or any other messenger).
That seems crazy for me. I like to do the 'serious' things by email as I can archive it accordingly, and it's easier to set calendar items and reminders directly from there. That would include medical and administrative things for sure.