

Restricting screenshots is laughable security. If you can read a message then you can take a picture with a second device, there isn’t any software that can stop that.
Preventing screenshots can stop accidents and make someone think twice about it, and disappearing messages prevents returning later and looking them up, but that’s it.
For services that are throwaway, this is fine. I don’t care if someone gains access to my ice cream rewards account, they don’t have anything else important. And I believe these services only last 10 minutes, meaning you can’t password reset them because the inbox doesn’t exist.