It offers higher-level primitives than e.g. OpenSSL. Instead of the primitives “ChaCha20”, “Poly1305” and “Ed25519 signature”, you get “authenticated encryption

It offers higher-level primitives than e.g. OpenSSL. Instead of the primitives “ChaCha20”, “Poly1305” and “Ed25519 signature”, you get “authenticated encryption” (implemented using ChaCha20, Poly1305 and Ed25519). You do not have to know or understand how to combine the three securely, nor how to combine everything down into a single parseable stream for the other end.