I say its because you cant pick what you want and you just get stuff...like one of the packages has an urchin...another has a sand sifting star...etc....so you will be getting things you may not need or want based on your tank.
And as far as I know, a cbs will not tolerate a peppermint unless in a large tank. Then again, I have a cbs that acts like a cleaner shrimp so who knows?