This is something I despise in general. Why? Because our minds do not actually all operate like that. It's hard to escape some small amount of bias, but it's fully possible to ref the play, and not the players, if you catch my drift. And it is something that is evaluated with refs at every level...as in, if you're reffing a high school game, and one guy is clearly dominating, some refs will be more influenced (even if not intentionally) into giving that guy a favorable whistle, and some won't, and this is something that's noted whenever you're evaluated for a game. In fact, they try to teach you to be as much like the latter as possible when you start reffing (at least when I did). At the NBA level, you'd think they'd do everything they can to ensure more of their refs fit into the latter category, but watching the games (of any team) it really just doesn't feel like that, at least not nearly as much as you'd hope.