That's a brilliant scene. However, I suspect most people aren't trying to convince/persuade/change the crowd either. Instead I think they're seeking approval from the subset of the crowd that already prefers vanilla. It's a pretty rare type of whore to be an effective lobbyist like that.
If one really did want to change the crowd for some polarizing current topic, I wonder how to go about it. It'd be easy to substitute Vi and Emacs for chocolate and vanilla, but I'm not seeing how to apply it for climate change, guns, abortion, free speech, the middle east, or really anything that people actually fight about.
The point of winning internet arguments isn't to convince the person you're arguing with, it's to convince the people who are watching.
It's just ice cream politics.
https://www.youtube.com/watch?v=xuaHRN7UhRo