How do apps like WhatsApp get popular? They offer inferior service in every way to builtins, and require that both parties have installed something. SMS is in every way better unless you don't have a texting plan, in that case, GTalk and iMessage are in every way better (And GTalk is even cross platform with several fairly simple XMPP clients on IOS). Who uses this shit?

I encountered the same thing recently with Raidcall. It's a shitty voice service that's in every way inferior to Skype, but trying to position itself as a competitor to Teamspeak (Which itself has been eclipsed on features and price by Mumble). Yet, somehow people will argue with you about it and evangelize it, without any sort of benefit comparison.