My argument wasn't that rethorical training is harmful, my argument was that the specific debate club version of it can be harmful if it isn't accompanied by education that developes the character of those who learn it (my personal opinion is that education that doesn't develope the character does not deserve the name).
There is a reason why such lessons are commonly used at "elite" schools like Eton¹. Getting clever at arguing your way into (and out of) things is undeniably a helpful skill for any position of power in society. But ultimately we should remember it is a two-edged sword: The better you make people at arguing, the easier it will become for them to lie to themselves. This is what will happen as a side effect, if they don't learn why they want to avoid lying to themselves, how to spot it when it happens and how to deal with it when it happens. This is not just a character-thing, but something that has to be tought as a core value.
¹: https://indianexpress.com/article/trending/trending-globally...
I don't think the rhetorical appeals to anger, hate and fear that are the hallmarks of genocidal leaders are learned in a debate class. They're low-level schoolyard bully stuff. They're exactly the sort of thing that's tempered by the conscience you develop if you are exposed to new ideas or have to argue something that's strange to you. Hateful rhetoric drives, and is driven by emotion. So is loving rhetoric. If you find you have to defend some group of people you previously had a loathing for, there's a fair chance you'll start to see things from their point of view, if only because it's human nature to become emotionally invested in what you're arguing about. (Check out any stupid bar fight where both sides know they're wrong, but are completely emotionally invested).
Yes, speech is a tool and a weapon. We should call out arguments made in bad faith; but we need more people who can identify them to do so.