Basically in a lot of Europe texting was or still is expensive and not unlimited and WhatsApp was a free alternative and Meta did not own it at the time.
So everyone was like well fuck texting and adopted apps like WhatsApp and then Meta bought WhatsApp. Now in these countries it's the defacto standard whether you like it or not. Businesses, people, and even sometimes government uses it as the default way to text. It sucks.