(Non snark ahead) Could this be why working at Google is no longer the prize it once was? And why developers would rather go to Facebook, Twitter, Dropbox, et al?
(Non snarky response) I dunno. I joined Google in 2008, and as far as I know Google was always like that. So, unless you claim developers have preferred Facebook etc. to Google for more than 5 years now, it's probably not related to the interview process.
http://www.glassdoor.com/press/wp-content/files_mf/133228554...
Also base rate is higher at Facebook, and interview difficulty is rated lower at Facebook.
Somewhat disappointing, as I'm a huge fan of Google.