I really dislike this trend of "oh we totally credit our sources here is a tiny link at the bottom of the article, never mind that it isn't underlined like all the rest of our links and it is in the same color and font as the word 'Advertisement' just below."

The source should be clearly defined and easily accessible, especially with these just-rewriting-the-source articles. (Glaring at you, Gizmodo and TechCrunch.)

Agreed in general, but the Medium author seems genuinely enthusiastic about the OP, so it was probably just an oversight. (Edit: and the phrase where he introduces the source article does link to it.)