Never thought I'd see the day that a pg essay crosses over with /r/politicalcompassmemes
The problem with "discussing ideas" as a framing is that it exists in opposition to something. What is that something?
Those whose position favours the status quo would read it in opposition to "not discussing ideas", which is obviously bad. However, to those who find the status quo untenable, the opposite position is "acting on ideas".
Following pg's example, let us consider the following classic debate topic: "is slavery good?" A plantation owner might find themselves tickled by a lively discussion on the subject, replete with a cornucopia of Enlightenment principles and classical liberalism and such. A slave might find this discussion less interesting, because no outcome would lead to their freedom.
It is perhaps telling that slavery was not abolished through free inquiry or the discussion of ideas. It was abolished through acts of state power and, ultimately, violence. Are we to believe in an alternate history where the South was debated out of its peculiar institution? The discussion of ideas gave way to acting on those ideas. The alternative would be a society of endless, meaningless rambling.
Today, if you were still debating "is slavery good?", you would not be a brave free-thinking iconoclast, you would be either an idiot or a very devoted racist. You would get uninvited from lectures and yelled at on Twitter, not because your ideas are too advanced, but because they're too far behind. The debate is over, and the actual free-thinkers have moved on.
It's sad to say, but I think the real lesson of this essay is that political ideas are just like music taste. Whatever your parents were listening to is outdated and embarrassing, whatever the kids are listening to is just angry noise, and miraculously your generation was the only one to stumble upon that which is profoundly, timelessly good.