It’s also just a more accurately descriptive word. Nemesis was the Greek god who punished hubris. A Nemesis is somebody who delivers (a usually unavoidable or inevitable) retribution to you. An archetypal nemesis is somebody you have wronged, and somebody who successfully manages to enact a retribution. I get that it’s come to mean basically any serious rival, but that’s dumb imo, and the original definition of the word is better.

For some reason, which is not quite clear to me, the author explicitly brings up the term rival and rejects it without any clear explanation.

> It has to do with what sportswriters and fans call rivalries. But I view it as something different—I refer to this same phenomenon as the Concept of the Nemesis.

Then he goes on to use the term rivalry a bunch.