The NFC dominated the league that year. The raiders played 5 NFC teams and only won against 2 of them, and one of them was Arizona. The other was a struggling Seattle team.
The 49ers, Packers, Eagles and Bucs were all better overall teams than the raiders that year. The Niners and Buccs both beat them during the regular season to prove that. I'll take away the Falcons and Giants so you're right, not any NFC team could have beat them in the Bowl that year. But 4 out of the 6 could have.
But any way you look at it, the raiders were not on top that year, like it or not.