Indeed. I just ignored the dialog box the first time it popped up. But next year I paid. It was quite a big deal because back then it was equal to my entire monthly cellphone bill in Pakistan.
But I remember other people started to en masse switch to other messengers like Viber(?). And Whatsapp had to stop enforcing the fee.
I was billed 0,99€ (Germany) exactly once, but was able to use WhatsApp without payment for most of the time just by ignoring the notification. I remember that they repeatedly gave grace periods and just set another payment date a few weeks later.
But I remember other people started to en masse switch to other messengers like Viber(?). And Whatsapp had to stop enforcing the fee.