Also in this case the problem is if a site has some text that's blue & clickable, and some text that's blue & not clickable. That's more or less what iOS 7 is doing. Colored text doesn't mean it performs an action. It might, it might not. Similarly, black text might be clickable, it might not. It might have a border, it might not. And these are all mixed together in the same app, or even a single screen such as the case of the alarm that the article is talking about.
A web developer can override both those conventions and when they do, their links become less recognizable and their apps become less usable. Since there's no cursor on iOS touch screens, losing the visual cues is a similar problem.
[edit] You might argue that just tapping on something serves as the way to discover if a visual element is tappable on iOS. But it doesn't, as the original article states, it just makes the user wonder if something might be broken.
They're not, and their relative ease of use is only because users have learned over years that a few words looking markedly different (but not emphasized) might just be links.