Originally Posted by
daka
"Steel ring teeth make sense; the smaller the ring the more sense they make. I suppose the best arrangement would be a U-channel ring of steel teeth with an inner aluminium ring and arms centrifugally cast into the ring and then machined and peened."
That is the intuitive response, but it may not actually be true.
It's not intuitive, it's economic. If one part is going to wear at the expense of another, let it be the cheap one. Chainrings cost more than chains.