The last job where I was doing performance reviews I accidentally did honest reviews with my guys, hoping the feedback would help them grow. Unfortunately, I was the only manager who did that, everyone else gave all of their staff glowing reviews, even the lazy and incompetent ones. My boys were the hardest working of the lot and suddenly I had HR wanting me to put them on PIPs!  

 That is a real shme. In that world it does not pay to be honest. Everything is playing the game. Saying enough to cover yourself but not so much that you end up where you described. 

And then you develop a personal relationship with these people and its not nice to think about how you could be moving them closer to being out of a job.