I am a layman in these matters, but I have a theory, and so I can only put it in layman language. Professionals will have to bear with me. My theory is that the very first requirement of being an influencer or a leader over others is that you have the ability to hold their interest. Perpetually, actually, if you want to remain in that role perpetually. I believe that you stop being able to influence or lead someone as soon as you stop being interesting to them.
Like a tweet that I read this morning says, the problem is remaining interesting for long:
Everyday we meet interesting people, the problem is remaining interesting for long.
— Peacock | @GenVoices (@dawisu) January 7, 2014
Remaining interesting for long is not a trait that a lot of people have. Remaining interesting for long to many people is difficult. Yes; other traits are required in order to lead people in some way, but it looks to me like it does not matter any other skills or abilities one has; if one is unable to hold the interest of people, one cannot be an influencer or leader over them.
The best engineer may not necessarily emerge the best leader among a group of engineers. The best lecturer may not necessarily become Vice Chancellor at an institution. Perhaps the one who remains the most interesting will get the role. Perhaps not.