> I've no doubt it may be the case in the US, I did not mean to suggest it's not. It simply doesnt have the same sway everywhere.

You're correct, of course. WhatsApp was significantly more popular than SMS in the majority of Latin American and European countries before iMessage even really picked up steam in the US. But it doesn't matter, because the US, by revenue share, is the world's largest market, full stop. One of the lessons we can learn from the social media business model is that you can get incredibly large entirely off the US market before it even makes sense to engage in the rest of the world.

The person you're replying to is correct in context of the US market, which if you're Apple is basically the only market that matters other than China, since in the rest of the world most people use Android, usually due to cost differences (flagship Android models sell extremely poor volumes compared to iPhones, even globally).