In office forever?

I read today on the web a comment in which a person stated that a president should remain in power for as long as people kept voting for him/her. This person's argument was based on the idea that if the president is doing it right, why he/she could not stay in power forever.

I am of the opinion that rulers -no matter how great they might be- are not infallible and because of that they should be held accountable for their policies and practices. If politicians remain in power for long periods of time they become so in love with power that they forget the reason of their election: service. When rulers stay in power for so long they begin to control many aspects of society making it difficult for the public to evaluate the administration. It also contradicts the democratic spirit that should be behind all political (and nonpolitical) races and elections.

Then my question would be why a person should remain in power for long periods? Why cultures ask for it? Isn't it clear that it is part of our social intelligence to be active members of our societies, to be critical, and to actually be responsible for electing capable politicians.