I paid 99c for Whatsapp on iOS years back. This was before IAP and I believe it was the only way to get it on the platform.

This is what I thought as well.

WhatsApp asked me for money a few times but wasn't overly bullish about it after I ignored it for a few days.

Not using WhatsApp isn't any obstacle as everyone seems to have a few messengers. I just pressed a different button, others answered on the platform I swiched to.

Good to so I'm not alone. Heck, I've even moved countries like 3 times and I haven't paid a cent.