It does seem like a narrow application, though 7.1% of U.S. adults is a lot of people, and sleep trouble is the first of five symptoms mentioned. Even if it is a gotcha, Walker walked into it with his confident language claiming that "thousands of studies insist that no, there aren’t" "any biological functions that do not benefit by a good night’s sleep." This is not the careful language that befits a scientist, certainly not a "Sleep Scientist at Google" as Walker styles himself. Aside: In June 2018, Walker's Wikipedia entry described his work for Verily Life Sciences, an Alphabet subsidiary. In July 2018, a user named Remdreamer changed the name to "Google Life Sciences (Verily)", and changed the heading from "Verily" to "Google". Since 2015 the Verily article used the description "Verily (formerly 'Google Life Sciences')." The word "Google" does not appear on the Verily home page — nor, for that matter, can I find Walker mentioned on the team page or in the blog. Remdreamer has edited no other articles.
Walker has at least partnered with Verily in conducting sleep research for Project Baseline. But yes, it was weirdly non-trivial to find public acknowledgement of his work at Verily.
as far as it being a gotcha, it's more just orthogonal to the question of whether sleep is good for you. an electric shock may get your heart moving again in an emergency, but i would not characterize it as good for you. indeed walker's language is imprecise
the number of depressed adults is one thing, the number successfully using sleep deprivation therapy is another googling "wake therapy" yields a lot of pop articles with the classic numerous studies say, but the studies all -- including the one guzey links in his response -- point out that the effect reverses after a while/a night's sleep. so i mean, if you get depressed once a month, then maybe pulling an all-nighter is fine and this is a godsend. but for chronic depression, which is what i assume "major depression" is... if this is the therapy you choose, say goodbye to your job. entertainingly, the relevant pdf from guzey's essay is hosted by gwern and has "illegal to host publicly" stamps all over it