We sue professionals. We sue doctors. We sue lawyers. It was recently reported that one of Joan Rivers doctors had faced a prior malpractice suit. Although we clearly believe professionals (including doctors) should be held responsible for negligent conduct, most prior claims of malpractice are not relevant to a different claim of negligence. Unless the prior claim of malpractice involved the same error it is of little value and many courts will say it is entirely irrelevant.
If I ran a stop sign 4 years ago it does not indicate a propensity to speed. I am not sure it even indicates a propensity to run stop signs. I made a mistake once. I should be liable for damages caused by my negligence (mistake) but it does not mean in a case involving speeding that it is at all relevant to say 10 years ago I ran a stop sign. Yes of course if I ran a stop sign at 4pm telling the officer I was late for a 5 pm meeting. If I then was speeding and caused an accident to happen, it would be relevant. But not if it happened many hours earlier or many years earlier.
So bottom line is that although it may be interesting to lay people to hear more about the players in a current story about a star, it is of no significance in a claim of malpractice.