> An argument, though, is an exchange of ideas that ought to surface insight and lead to a conclusion.

That's one definition, I suppose, but it's not the definition you'll find in any dictionary I've seen. The author here seems to be assuming that the only valid reason to argue is to learn. People argue for many reasons other than that.

> If you’re regularly having arguments with well-informed people of goodwill, you will probably ‘lose’ half of them–changing your mind based on what you’ve learned

Again, the author's unspoken presupposition begs to be questioned. Why do most people actually argue in the public sphere? For instance, why do we have presidential debates? The candidates certainly aren't there to learn. They are not even trying to persuade their debate partner. They are arguing to convince or persuade their viewers of something. These could be undecided viewers, or they could be viewers who have already made up their mind but may either feel strengthened about their beliefs or weakened after listening.

Similarly, if I'm debating someone online, it's often less to convince that person and more to convince anyone else who might be reading. I have heard of people in real life who have read debates I've engaged in and expressed both gratitude for my willingness to do so and that they were strengthened in their beliefs on the subject.