You get it, but you don't see the relevance. Alice uses a smartphone and a laptop with WhatsApp. Bob only uses a smartphone with WhatsApp. Alice and Bob discus

You get it, but you don't see the relevance. Alice uses a smartphone and a laptop with WhatsApp. Bob only uses a smartphone with WhatsApp. Alice and Bob discuss something secret. Alice assumes only Bob's (secure) smartphone can read the data. Bob assumes only Alice's (secure) smartphone can read the data. They both got physical access to the smartphone, which lowers the attack surface at that moment. Alice's laptop is in her house. As is Mallory. My problem with above isn't that this works; it is how it works. My problem is that Alice never temporary authorizes WhatsApp Web. My problem is that Bob doesn't know about Alice's 2nd device. These 2 issues are issues which can be addressed and raise the privacy of the data considerably. The gut reaction "oh, its E2EE, so its secure." is dangerous, and untrue. Yes, I'm aware you can make screenshots and print chats. You can also send temporary messages with Signal though. That's on top of E2EE, because E2EE isn't a panacea.