While delving into the above question, I am restricting myself to the political elite only as the contemporary example that has led me to think about this is related to politics (power relationships in social sciences). Though, I admit that this is a common symptom in all elite and I also know the answer for this behaviour to some extent. The present example is that of the external affairs minister of India Mr. S. M. Krishna who read the speech of the Portuguese minister for 3 minutes (of course, by mistake) while addressing the UN Security Council. Please follow this link to know more about this incident.
It is wrong to blame Mr. Krishna alone as it has become a tradition to read out speeches written by anonymous person/s. While getting a speech written by someone to be politically, gramatically, technically. —-lly correct is not unwelcome, the inputs that form the spirit of the speech have to be provided by the speaker who is a people’s and thus nation’s representative in this case. I also had the ‘boring privilege’ of listening to Dr. Manmohan Singh at the passing out parade at IMA, Dehradun from where my friend was passing out after 18 months of HARD training. Leave apart getting encouraged, these gentlemen cadets did not follow anything of what he said. I know that the prime minister is a person of impeccable integrity and with a very good knowledge in economics. But, a leader also needs to encourage his followers by both his speech and acts. Contrast him with another leader which India saw who laced his speeches with poetry or another leader who is well known for adding humour to his speech. I am desisting from naming these leaders for I may be charged of being biased towards some political party.
My initial reasoning for this behaviour is as follows. As we go higher the organizational hierarchy, our understanding about the ground truth goes on getting blurred and at some point, you are totally cut off from the ground realities. In such a case, some other personalities become your eyes and ears. (In case of Mr. Krishna, it could be the external affairs secretary). Also, at this level of hierarchy, public opinion outweighs individual opinion and thus relying on the input of someone else whom you have delegated the power of assimilating information becomes inevitable. But this does not mean that you do not apply your own mental faculties (provided you have them :))