You're saying that email, text messages and phone calls don't work as well as WhatsApp for small businesses? I wouldn't have expected that, so I'm curious if you have examples to share.
It's a country specific thing. I find that my clients in the US generally prefer email, Slack, and Zoom/Google Meet. Clients in India, South East Asia and Africa, and some parts of Europe (Italy comes to mind) very strongly prefer WhatsApp even for business communications.
