Even without WhatsApp for business, it's changed the world. I'm an American in the US and have multiple messaging apps on my phone, but have recently taken recruiter calls via WhatsApp from overseas headhunters. It was surprising, and I'm still a bit befuddled when my phone rings and it's an app that isn't indicating a POTS call, especially if I haven't received a text message in advance to let me know it's coming.