Basically, it claims that double major is a fad, based on student belief that a second major helps them in the credential-for-employment arms race.
More articles on double majors:
https://www.chronicle.com/blogs/next/2012/10/11/the-worrying-rise-of-double-majors/
http://theconversation.com/does-it-pay-to-get-a-double-major-in-college-74420
http://nation.time.com/2013/01/31/should-colleges-ban-double-majors/
At least one university has found that double majors have been declining over the longer term:
https://www.stanforddaily.com/2012/11/05/double-majoring-sees-downward-trend-since-1980/