Things I'm too polite to say out loud;
"You may think everybody uses Whatsapp. Someone else may think everybody uses iMessage. Someone else may think everyone uses Instagram DMs. Saying that everyone does or should use a specific centralized messaging app is discrimination against those who know better or simply have different preferences. Following the pack for the sake of following the pack is always a bad idea."
The smartest messaging method is not a segregated mess of WhatsApp, Signal, Telegram, SMS, Slack, Teams, Facebook, Instagram, WeChat, etc.