Yes, this is the actual reason that copyrights aren’t infinite. It just seems hand-wavy, full of assumptions, and rather vague as a justification from the creator’s point of view.
What I’m hoping for is the kind of clarity and specificity behind “makes the world a better place” that could actually be used to guide thinking about how long copyrights should last. Right now, the article and this entire comment section feels more like an argument over personal opinions and assumptions, and lacking enough evidence, enough historical understanding of copyright, and enough philosophical rigor to justify a specific number of years.
BTW, I completely disagree with the article’s framing of “first order” and “second order”. They are reversed, as a persuasive tactic, but incorrectly so. The first order effect is the money and content value that changes hands as part of the transaction on offer by a creator. Letting the public at large benefit from free copies is both an economic and a temporal second order effect that doesn’t have tangible value, and comes with some economic harm that requires balancing.