It's not about having accounts. Again, the data source (which I admit could be wrong/misleading) all say active users, which I take mean users actively sending messages using FB messenger. The sources, by the way, are companies that sell services that market to consumers using these services, so it's in their interest to know usage stats and patterns. Admitedly finding information around iMessage usage is harder, which is why I went with number of active iOS devices. Yes, it's sketchy AF, but I'm not going to pay Statista $149 in a vain attempt to pyrricly win internet points.

How? 140 > 136! And the figure reported are active users. I accept it's back-of-the-napkin, not trustworthy sources, but even so, your math just doesn't make sense.