The success of the first process is wholly contingent upon establishing the validity of the identity of the private key recipient. While many vendors have products that perform many of the tasks required to accomplish those goals, you can't be certain that their products interoperate with other vendors' products that may be in use at companies with whom you conduct business. There are other encryption schemes like Symmetric Key algorithms or elliptic algorithms, but they're not widely used. Authentication is used when logging onto a system or with devices such as badge readers or other types of hardware. Certificates may also be used to establish the identities of each end of a secure transmission tunnel.
Confidentiality protects the contents of a document.
E-signature allows everyone to see the document, but also allows everyone to be sure where it came from. This all assumes that my private key stays a secret and my public key is known, and accessible, to the world. No PKI hierarchy is required, so no one needs to certify the identity associated with a particular key. PGP works by individual trust. You know the person who gave you the key and you trust them.