The point of the article was that Etsy has already established both sides of the marketplace. And that both sides of the marketplace are not equal, as competitors/disruptors are discovering.

To be successful, they need a large consumer base, and a small seller base, who sell high quality goods (which is subjective, but mass drop shipping is certainly not what those consumers are expecting).

Of those, the hardest to attract is a larger consumer base. Sellers will ultimately go where the buyers are.