In a real and ideal situation, those who criticize government are suppose to be those allowed to show what they have to offer because it may seem that they have better idea. I said ideal because assuming the system is not corrupt, so that they can genuinely offer something positive to growth of the country but the problem is when such person get into power or government and meet bad system, they eat their words and start doing the same thing that they have criticized or they are frustrated out of the system by those who are feeding from the corrupt system.
A vast majority of the problem lies in the system and just like you have said the action of the leader is mostly controlled by the system on the ground and most problems that we think are leadership problems are actually system problems and to start with, any country that you see it government losing legitimacy from the citizens such countries have one thing in common which are faulty constitutions weak institutions.
More also a lack of national developmental goals, all of which is what gave room to bad leadership since the system could be bastardized at will.
We have both identified that there is problem in leadership and this is especially in third world countinent although some of them have tried to put their system right like South Africa. But majority of the leaders in other countries don't want to cause a change to happen rather they want to keep benefitting from a bad situation, they rig themselves into power and want to subvert the constitution yet they don't want a military rule. They are civilian government in outlook but military in process and in their minds and because they have that military mentality to subjugate, they go after every of their critics that was not able to run to asylum and put them in jail without proper and public trier.