Only if you have an adversarial relationship with your correspondent.

I do not see how this affects it. As a matter of fact, if you do not have adversarial relationship with your correspondent you would not need that piece of drm.

Mostly people don't particularly want to betray you but they're lazy and don't care very much about you.

As a result "please delete this message" won't get actioned but exploding messages can be very effective.

When I'm flying at the airport, a border guard can compel me or my friend to unlock our phones and show them all our messages. If our conversation history is regularly automatically cleared, we can both have peace of mind.

I don't know how you can have peace of mind giving your regular phone to a border guard in any case. If you travel on any regular basis, a dedicated phone for travelling that gets wiped before crossing borders is well worth the purchase, IMO.

Disappearing messages do help with your friend who doesn't have a sanitized device.

and your friend who has a gf/bf that goes through their phone taking pictures when you are asleep or in the shower, whether you know it or not..

and other apps on your phone that behave the same way.