[Wisdom of Wizardry]

At the risk of being deleted for having nothing to add, I will just say that I agree that Sam could not have destroyed the ring, as he would not have been able to overcome its power any more than Frodo was.

In fact, I think the ring destroys itself; and I think this is the final dramatic restatement of a dominant recurring theme in the books: that evil eventually turns upon itself and brings failure to evil intentions. "Oft evil deed will evil mar".

This is foreshadowed in the wasted lands, when Frodo requires Gollum to swear upon the ring to be faithful in leading them to Mordor. He says "The ring is treacherous. It will hold you to your promise".

So, when Gollum wrests the ring at last from Frodo's maimed hand, thus betraying his promise, the ring exacts its revenge on him to its own final destruction.

A very neat fulfillment of the oft-repeated theme; and fitted exquisitely into the story.