Katz started the research focus on skills during a time when there finally was a definitive list of leader traits described in the literature there was no research yet on the individual attributes of leaders there was emphasis in the literature on putting followers first there was still disagreement about leader traits in the literature

I believe the answer is There was still disagreement about leader traits in the literature
For example, in the past, researchers fail to attribute physical traits such as, Facial feature, height, and weight to effective leadership. Recent science shows that good physical traits tend to attract attention from others and give more commanding presence that could make someone's percieved as an effective leader.

United states v.  nixon, 418  u.s.  683 (1974),  was  a landmark  united states supreme court case  that resulted in a unanimous  decision  against president richard  nixon, ordering him to deliver tape recordings  and  other subpoenaed materials to a  federal  district  court.