I can only guess that people sending messages to my cancelled WhatsApp account saw only one tick. That's still meaningless to less skilled users and there's no way to tell if the user has gone forever or if they're just offline for a bit.

Anyway, my point is that WhatsApp shouldn't silently accept messages for a non existent user no matter what weak signals you get. When you send a text message to a non existent number, you get an error. Same for an e-mail.

I can't help but think it's a way to deter users from leaving WhatsApp.