Disclaimer: I'm an investor and board member in @MFineCare, so obviously am not a disinterested observer.
There are two main reasons for this: clinical and economic.
My neighbourhood grocery chettan takes orders on Whatsapp. But imagine if he needed to know which toothpaste I used 12 years ago, had to give me a signed bill every time and constantly needed to go back and look at my previous order. Healthcare is like that.
You can't do any of this with a Whatsapp transcript, leave alone an ephemeral video call that vanishes as soon as it ends.