Comment by j45

BBM was the iMessage and WhatsApp before either of those.

WhatsApp became popular specifically because it was a multi-platform replacement for BBM.

BBM had little else to offer in terms of apps. It was a corporate ecosystem and good at that part of it.

iMessage also came out after BBM, and did their own device lock in, except iPhones were designed for the many instead of the few, especially beginners to smartphones.