Many encryption technologies rely on the trust of an external Third-party. For instance the security of secure end-to-end TLS connections relies on the trust of a Certificate Authority (CA).
Trust No One design philosophy requires that the keys for encryption should always be, and stay, in the hands of the user that applies them. This implies that no external Third-party can access the encrypted data (assumed that the encryption is strong enough). Trust No One also implies that an external party cannot provide a backup mechanism for recovery.
Although the philosophy of Trust No One at least assures the Confidentiality of the communication of the user that creates it, in real life and in society many communication means rely on a trust relationship between at least two parties.Trust No One is also often part of Zero Trust systems.