Yes because both power and influence are recipes for leadership. To achieve leadership success, one must have the power so as to be respected and also one must be influential so as to lead others.
Is an understanding of power and influence critical for leadership success? If so, how?
Yes because you need to know how to manage those things. If you don't you can never become a good leader because as a leader you have power and influence. You need to know how those things work so that you can use them for the good of the group you are leading.
To be a successful leader you need to have confidence in yourself and your beliefs and people will believe in you..if power and influence is what makes good leadership then that is a scary prospect..I wouldn't respect anyone who had those beliefs...