rainborick - 3:00 pm on Sep 13, 2013 (gmt 0)
I think there's a simpler explanation. When Google started to aggressively penalize sites for incoming links, the webmaster community started to buzz with complaints that it was too easy for competitors to sabotage their sites by posting bogus links. So Google adjusted their automated SPAM link detection system to first notify webmasters when their site was about to undergo a manual review on this issue. That would give the webmaster a clear warning that there was something unusual about some of the links pointing to their website, and gives the webmaster an opportunity to bring the site into compliance.
Every situation is going to be a little different, of course, but whether or not a webmaster is truly guilty doesn't much matter. If Google thinks you're guilty they're going to penalize you unless you bring the site into compliance with the guidelines. And if you do get penalized, the path to getting the penalty removed will likely be a lot smoother if you demonstrate your intention of bringing the site into compliance from the start.