To the extent many people think they have some chance of reaching the very top, political and party mechanisms may attract more first-rate talent. Furthermore, information transmission decays when more and more of the rent-seeking is aimed at the very top person, and that person does not turn over with time. Do not report the complete truth! That rise in toadying further discourages top talent from entering into political competitions.
When this happens, it is also a sign that a political system has lost some of its ability to protect autocratic leaders after their terms are up, so this can be as much symptom as cause of bad events.