A pure moral play, and well written and acted to make the central lesson effective.
For a civil society to function, a person cannot make his own rules or laws. Essentially, what could have been was rendered destroyed, because the central character continued to make the choice of rejecting civilized redress to criminal actions carried out against him.
Through his charm and otherwise solid character, he turned a one man revenge tale into a far more tragic ending, when a completely innocent person becomes victimized.
In one particularly poignant scene, the central character openly asks what the difference was between him and Matt Dillon. He never answered his own question, but instead remained convinced it was a mere matter of "luck of the draw."
The episodes' finality illustrated the true difference. Even at the end, Dillon urged the man to "drop the gun belt," and surrender. One man never wanted to follow the law, while the other was honor bound to enforce it as well as adhere to it. That was the reason why the two characters ended up totally different.
Another of the episodes that made Gunsmoke immortal. An excellent piece of morality expertly played out, with a valuable lesson provided.