The problem is that everyone assumes you have WhatsApp.

You take clothes to the laundry? The “your order is done” notification is sent via WhatsApp

Any kind of work stuff is also on WhatsApp

You order food delivery? WhatsApp

Amazon started to send delivery notifications via WhatsApp instead of email/sms

And luckily meta is charging businesses 5 cents for messages via API or otherwise even otp codes would be via whatsapp

At least here, being reachable only on signal means being a digital exile