Everyone bitching about the lack of underlines and not using blue or purple needs to step back and notice that none of those link examples were shown in the context of non-link text.

In the context of surrounding text, it's entirely possible that these link effects are as usable as underlined text.

Design is about concepts like contrast, repetition, alignment and proximity. The designer here left the use of design principles like contrast up to other designers to choose how to indicate that a link is a link.

Contrast makes a link look like a link. Not blue, not purple, not underlines, but contrast.

Besides contrast, context matters too. There are words and expressions which are often linked, such as proper noun phrases, references to other works on the internet, obvious link phrases like "click here", etc. Once you've read one utterance in a different style on the page that is likely to be a link, then you have enough information to mouse over or try tapping and verify your hypothesis. Once you've verified the link style on a site once, you don't need to do it again.

Humans are pretty intelligent pattern matchers, and so long as the designer has placed enough clues in a page to identify a pattern, that is good usable design.

FWIW I don't disagree that it would behoove the designer to make things explicit by showing his links in example contexts, but that doesn't excuse everyone showing up here raining on his or her parade because they lack the imagination to see how these could work in context.