Well there are uses for magic arn't there? Not everyone gets to be left alone for 30 turns to make supergolems

The reason that Arco is very nice to learn on is because of the wide variety of magics. The reason that the Natty is so good to learn SC's with is because he's very, very solid with a few picks of the right magic and has the slots to switch/adjust.

Combine a Natarajah with the versitility of Arco and you have a lethal combination for learning about SC's. Not to mention the standard armies of Arco can very much hold their own without much need for support from indeps. It is a much better breeding ground for learning alot of what the game has to offer as far as making tough combatants in combination with standard armies and magical choices.