Best summary I've seen. There are two significant facts here that surprised me:
1. The double checkmark has security implications. How would a typical user know that?
2. Even if you are completely vigilant, follow best practices, etc, Whatsapp messages can be intercepted. They claim this is a "wontfix" UX choice. I'm skeptical why the non-default feature cannot even provide the protection that almost everyone assumed it would.
I think that's basically the main problem: there is no way to get a typical user to understand security implications of anything without having that user give up before reaching that point...
