Perhaps Johnny says it best from his deathbed after Pony and Dally jubilantly report to him that the greasers defeated the Socs at the rumble.
"Useless... fighting's no good..."
Both the Socs and the greasers recognize that the rumble will solve nothing (other than the Socs' promise to stay out of greaser territory). As Randy has already told Pony,
"You can't win, even if you whip us. You'll still be where you were before--at the bottom... So it doesn't do any good, the fighting and the killing... Greasers will still be greasers and Socs will still be Socs."
The rumble did little but to create further hatred within the two groups. Pony, meanwhile, realizes that the Socs are no different from the greasers: He has managed to become friendly with both Cherry and Randy, and he likes them both. The deaths of the three boys has taught him that violence only leads to more violence, and Pony's desire to honor the truce between himself and Darry shows that he understands that a peaceful solution to a problem has a much better chance of succeeding than by more violent means.