It’s impossible to overestimate the future. - Claude Shannon

WhatsApp is secured with end-to-end encryption. Even more importantly, there is the ability to swipe (even from the lock screen) to reply to a message. Due to this feature, it is clear what text one is responding to. I believe this feature pushes discussions on WhatsApp over the finish line, to being more productive, rational, and less ephemeral/forgetful than face-to-face discussions. Just like paper was a better medium for many things, so is this new digital medium. But that is an (almost) philosophical aside. I believe, due to the ability to respond from the lock screen, it is incredibly efficient to communicate quick updates through WhatsApp.