In my own experience we in Europe don't care much about which phone other people are using. Of course we are defending the reason why we have either an iPhone or more probably an Android but all messages have the same color on WhatsApp and everybody kind of must use it in my country. I knew that there were European countries with a FB Messenger majority (France?) but I don't know if it's still a thing.

Having to use WhatsApp removes a reason to have to buy an iPhone and adds a new one not to care about the brand of the phone.