It is crucial to note that, when town squares were actually a thing, ie, a real place where people went to see other people, two things were true:

2) There were pillories, beatings, excommunications and other regulations that made those town squares nazi-proof, unless the town liked nazis, then they were jew-proof. Never in human history has there been a public venue where people were not disciplined for unpleasant views and attitudes.

1) There were no other communication tools to speak of. No phones, no cars. The town square was the only place to see people you don't already know.