alt Hacker NewsWhatsApp could exfiltrate messages at the ends. But I assume the trick lies in the word "default". Didn't Skype also default to end-to-end encryption, unless there was a server flag that disabled it for that specific user (I might be fuzzy on the details)
I don't trust un-auditable client applications...
If you want to assure me your e2e is secure, there must be at least two clients implemented by different people, with at least one of them opensource.
Whatsapp used to have this, but lately they have cracked down on third party clients.