I'm having a very hard time thinking of any positive social change that happened without individuals being called out. Take dueling. The Church preached against it for hundreds of years. Right-thinking people decided it was a bad idea. The government outlawed it. But everybody was afraid that if they didn't challenge people who insulted them to a duel others would think that they were cowardly, so they kept doing it.

But then people like Duke Wellington started getting publicly mocked in the papers for engaging in duels and the practice died out almost immediately.

So, talking about how people in general ought to be nicer won't actually change how people behave. Calling out githubuserxyz for being an ass, though, will make people afraid of being mocked like githubuserxyz and so actually change their behavior.

Seriously, there's an excellent book called The Honor Code about how these things happen historically that I would recommend.