Of course the gate in ancient times was where everything happened. That’s where people met one another, where commercial transactions took place, where community business was transacted, where the judges held their sessions. A reminder comes in the Aramaic prayer of Yekum Purkan, said on Shabbat, which prays for the “judges at the gates”.
People who had a problem didn’t need to go through a bureaucratic rigmarole in order to get a day in court. They knew they would find a judicial facility at the city gate, and no-one needed to feel that legal delays would deny them justice for lengthy periods.
How can one suggest that such an important provision was almost unnecessary?
Because such was the Jewish nature that no-one could imagine a community that had no judges. Did they need a law to lay down what was already instinctive? It’s not just that the administration of justice was one of the Seven Laws of the Sons of No’ach at the beginning of the Chumash. As SM Lehrman writes, “The Jew by nature is a law-abiding citizen”.
Even without a verse in the Torah, our law-abiding instinct would have ensured that we had courts and a justice system. Even the antisemites know that law and justice are intrinsic to being Jewish.