I've read masters of doom. Why does the Sweeny/CliffB partnership work, while Carmack and Romero failed?

My guess is ego impacted by fame, Sweeny/CliffB managed to not be quite as personally famous as Carmack and Romero. While I play video games, and recognized Sweeny/CliffB it took a search to place them as the fathers of Epic. I recognized Carmack/Romero without the need of Google.