...which I can't quote directly. Esentially Tolkien's position was that
Frodo did absolutely as well as anyone could have done, so although he did not
quite achieve the quest, he bore no blame for being overpowered in the
end. And also he can legitimately be praised for carrying the quest to
the point where it COULD be fufilled. In the end, though, it is
essentially Providence, not mortal strength, that wins the victory; a fairly
straightforward little moral lesson.
The Ring didn't havve much leverage on Sam, but we can
assume that he would have failed as a Ringbearer. Perhaps the Ring,
frustrated with such unpromising material, would have 'left' him as it left
Gollum.