This is horrible logic and ignores important opt-in/opt-out dynamics which are critical to our conception of privacy. By enabling "self-destruct," (or "disappear") the sender merely forces the recipient to "opt-in" and take affirmative action in order to archive the message (i.e. Screenshot). This is how telephone conversations generally work -- no recording unless one party takes action to tape it. Despite this ability to tape, we certainly still consider telephone to be more "secure" due to this archival distinction. Very often it is the advice of lawyers to avoid putting something in writing, and communicate it in person or over the phone instead. Disappearing messages brings us closer to this desirable ephermerality.