Following Google Guidelines
Face it, we've all been guilty of trying to game Google at one time or another. In all fairness, I have to say that in many instances it was a complete lack of clear direction from Google that lured even those SEOs with lily-white hats to occasionally dip their toes into murky water. And when those timid forays resulted in better rankings, some not only jumped in with both feet, but encouraged others to join them in the fun. Before you knew it, everyone who had ever heard of Search Engine Marketing was diligently following best practices that were not really best for anyone except spammers.
But this is the nature of SEOs, isn't it? We're like accountants who are always looking for loopholes. Only in our case, it's tactic...