<Snipped quote by Willy Vereb>
I liken it to the Skallagrim vs DJ fight, again. A Gothi vs a team of trained veterans; CHo was the main one, leader as it were, and even though the rest were trained, they were still considered NPCs. If they weren't, and were more or less considered individual characters, that would have been a wholly unfair fight.
The main reason why additional characters are classified as NPC's is because multiple people, with team work, would stomp a single opponent. Unless they were way way above your level. It would be unfair.