It does seem odd that there are people that physically harmed others that still have their works widely accepted, meanwhile those that were sometimes mean will likely never work again and people try to downplay the part they had in their work.
While I do feel people shouldn't be unpleasant to their employees, most people have worked for a boss that was a jerk to them at some point. I'm certain I was demanding enough of people in the past that if I was a celebrity it probably wouldn't look good.
From the article linked above, some of the people complaining about Joss seemed to lash out in more subtle ways at him as well, and had their feelings hurt when he didn't think their input was as important as they thought it should be.
The one thing that Hollywood seems not to be learning from these is that it isn't as much about the individual people but the structure of their business as a whole where when people are successful enough at making money for the studios, nobody questions the environment that they create, simply because they don't want to mess with the golden goose.
In most of these situations, plenty of people, with the power to correct behavior like this along the way, ignored it because there was money to be made.
