Yes and no. It’s true that Diffie-Hellman preceded RSA. But, my article is about encryption, not symmetric key agreement. The Diffie-Hellman exchange would require three courier runs. From A to B, from B to A, and again from A to B. The first two establishes a symmetric key, and the last is for delivering cipher-text encrypted with it.

Furthermore, if you read the Wikipedia article about the discovery of public key encryption, as I just did, you will see that actually it was discovered a few years earlier by two mathematicians, but not published.