You're glossing over the author's solid point on the nature of design, that over-engineering can stifle creative input. In the example he provides, the users became distracted from the purely photographic form of communication by a text-based one.
I like a related point I think he makes: that adding a feedback mechanism to a photo site turns the site from being about photography to being about feedback. In other words, it moves from being a site where people post photographs they like to a site where they post pictures they think others will like.
Seriously? Curtis lauds people writing a comment on a scrap of paper, taking a photo of it as a means to circumvent the lack of a commenting system on a website and hails it as "Photography's Third Act"? Wow, just... wow.