Why can't US experts remember that reading builds vocabulary?

An Edweek blog post (h/t SK) asks, "What are the best ways to help students -- mainstream and/or English Language Learners -- develop academic vocabulary?"  The author of the blog answers the question himself, then offers advice from a number of a number of other experts.  In the blog post proper, five experts offer advice; not one mentions reading. 

Instead, we get wisdom like "Select vocabulary strategically."  Hm.  There is also a wonderful Freudian slip in the author's step-by-step instructions in how to teach a word list.  He would have us first ask kids what they think the words mean, and then: "The following step is to illicit these student ideas and and guide them toward an accurate definition of each word, which they then write down."

Only in an appended group of reader-tweeted responses to the questions does someone finally remember that reading might be a good way to learn academic vocabulary: "Students develop their academic vocabulary best by reading academic texts on topics they are interested in."  Curious, I looked up the tweeter.  Who was this wise person who remembered reading?  Not a US expert, but "first and foremost a a family person: a mother of two wonderful boys, my husband’s wife, a daughter, a sister, an aunt…" She's also, in her professional capacity, a reading teacher in a college for tourism studies in Slovenia.

Why can't US experts remember that reading builds vocabulary?  Why is it only professors of tourism studies in Slovenia?!