What actually gets destroyed
In messaging apps, self-destructing usually means the app hides old messages and asks the server to delete them. In dedicated secret-sharing tools, the mechanism is stricter: the stored ciphertext is deleted from the database after a set number of reads or an expiration time, and the link stops working permanently.
The difference matters. A hidden message may survive in backups and sync history. A deleted ciphertext is gone, and without the ciphertext, nothing on the server can be decrypted regardless of what keys or URLs circulate later.
Everyday situations that call for it
Self-destructing delivery fits any moment when a secret needs to cross a channel that keeps history: sending a Wi-Fi password to a guest, handing a verification code to a family member, passing credentials to a contractor, or moving an activation key between your own devices.
It is not for everything. Conversations that need reference later belong in durable storage. But for the large category of secrets whose value expires the moment they are received, deletion after reading is the honest default, and it costs nothing to adopt.