The author provides good edge cases where theories once labelled as conspiracy theories proved to be correct. The conspiracy was true. And since many legitimate theories, in science for example, turns out to be wrong, the author asks: "Why do people pick on conspiracy theories?"

I think there is a problem in wording here. A conspiracy theory is, literally speaking, a theory about a conspiracy wherein bad intentions have led to error, lies and falsehood.

The key here is the charge of bad intentions. When Lamarck formulated his nowadays (mostly) refuted theory of evolution, I doubt anyone ascribe to him bad intentions. He was acting in good faith and did what a good scientists should do: show his work, enable refutation and critique. When someone suggests that the Face of Mars was covered up by a conspiracy, it is no longer a question if there truly is a depiction of a human face on Mars or not, but rather about someone's bad intentions.

So a conspiracy theory is a moral judgement of some social actor masquerading as a theory of facts. Moral judgements can be good and proper, but they can also be bad and uncomfortable, and they can challenge the self-image and narrative of a given society. That is true regardless if the specific factual statements are correct. To throw out an "edgy" and admittedly dubious suggestion: if the degree of falsehood in the justification of the Iraq War had remained hidden, maybe current distrust in US/Western governments would be reduced and contemporary polarization and conflict would also be reduced. As I said, I do not claim this to be so, but if it was true, then with some utilitarian moral philosophy, we might say we would be better off if the conspiracy theory never gained a following. It is not about the facts, but about the disruptive nature of the implied moral judgement of the conspiracy theory.

Therefore some conspiracy theories are easier to accept. The occasional tinfoil hat and manic street preacher adds to diversity and a nice urban aesthetics. A revolutionary uprising and terror not so much.

So I think the author has a few good points to add, but that the author's argument is too narrow when the conspiracy is viewed as only a conflict over facts.