I speculate that CG thinks that top arena position is not something to be attained by possessing 1 team that sits at the top with a bunch of good mods. "Oh I have THE DR/MALAK team and uber mods therefore I win #1." I believe they intend on it being more complicated than that. Perhaps something like having that team and another similarly powerful 1 like GAS that can be used to counter some other teams more effectively.
I believe they don't want anyone to be able to say, "Yay I have GAS now my roster is #1 in arena." My shard currently has 2 GAS teams in top 10. 7 DR teams and 1 Ig88 team surprisingly enough. That seems awesome to me.