It's a great observation, but I think the cause runs a bit deeper than the author attempts in this short piece. The issue is that academia has grown a lot over the past several decades [1]. Federal funding has approximately doubled in the past two decades, and the annual number of PhDs has increased by ~50% [2]. At the same time, the number of tenure track faculty positions in the US has nearly halved [3].

So you have a situation in which we're training a lot more PhDs, so mean research group size is growing dramatically, but we're offering fewer of the sort of academic jobs that can allow them to excel in their trained discipline. As these folks then leave academia, they're very often leaving for jobs outside their field. This is a really unfortunate loss of the incredible taxpayer investment in their education that we should all be supporting, not discouraging.

[1] http://www.aaas.org/spp/rd/fy2014/fedperf14p.jpg

[2] http://www.nsf.gov/statistics/infbrief/nsf10308/tab3.gif

[3] (embarassing wiki link, since labor statistics are a nightmare to sort though) http://en.wikipedia.org/wiki/Tenure_(academic)#From_1972_to_...