It is almost like it is by design that the system would draw in and select pirates that either wanted to left alone or abused their power and oppressed more people than they helped. The point of the warlord system was to create further divisions in the pirating world and make kingdoms more reliant on Marines for protection as well as make it harder for people prosper. For example, Alabasta and Dressrosa both of which had good leaders that were attacked by Warlords. You don’t see corrupt kingdoms being taking over by warlords.
The point of the warlords is to further divide up the world and cause problems not to solve them. Also why would the World Government care that common people are being hurt when they themselves have slaves and see the people of the surface world as dirt? They are worse than Doflamingo. The Celestial Dragons, the Five Elders, and Im benefit off slavery, weapons, and war. The more chaos the warlords cause the better it is for them. The warlords were always to bolster their own power never to keep peace.
–The Yonko
Same thing as above. The Yonko have territories that are held captive by the Yonko for decades further dividing up the world and making it harder to connect people. And they do messed up things like the Celestial Dragons and the World Government. Remember the Yonko aren’t as much of a threat to the World Government as we are lead to believe. Sussy went to Big Mom’s party. CP0 trades for weapons in Kaido’s terriority. Shanks doesn’t go against the World Government and is even allowed to talk to the Five Elders in person. Blackbeard is Blackbeard. They are kept under tabs and watched but are never actively pursued because their corruption helps their corruption. And if one of them poses a threat like Whitebeard trying to prop Ace to be the Pirate King, the World Government goes after them.
–The Marines
They exist as a way to control people’s perception of the World Government. Marines are given credit for taking down threats (like Crocodile) and covering up threats to the World Government (Ohara). We never really see Marines going to war to help free governments from tyranny or help people on a large scale.
–The Balance and it’s Purpose
The point of the balance of powers was never to help people or keep the peace but to divide up the world so that people are either always fighting or staying in their place. The balance the Five Elders talk about is not making sure that the pirates and marines are always equal but to make sure that there is always enough problems that people are not uniting. And this is why Luffy is a threat to the balance because he is going around taking down corrupt marines (Morgan), pirates (Arlong), kings (Wapol), warlords (Crocodile), spies (CP9), and in the future Yonkos.
He is also uniting people. That is why he is a threat. For example, if Kid took down an emperor, the world government won’t care as much. He is not a threat to them. The point of the balance is corruption and the continued cycle of oppression. That is what Imu wants. To continue the cycle and keep the world divided. All the systems designed by the World Government are designed in that way. The balance is only maintained if everyone is separated. That is also why Dragon is the most wanted man in the world and not someone like Blackbeard or Kaido. He is showing people another way to be free of the cycle of corruption and oppression. Corruption isn’t an accident. It is by design. Im fears unity.
–Im-sama vs Luffy
I don’t think Im is going to be a some mustache twirling villain. Oda adds depth to every character and I am sure it is going to be more than a good vs evil fight. Something that makes a good villain is that they are opposed to their protagonist on more than the basic good vs evil level but a philosophical and moral level. Luffy wants to explore the world and make as many friends as possible. In the Marineford war, Mihawk states that Luffy’s strongest power was to befriend even his enemies or in others words bring people together.
So if you think of the opposite it would Im someone who divides up people and box people in. Luffy wants freedom. Im wants continued cycle of oppression. I think this will be the conflict with Im. Im will try to convince Luffy that the world is corrupt by nature and all systems whether or not, they are built with good intentions will fall into corruption. That there always needs someone to sit at the top and so on. And the cycle of oppression cannot end because there is always someone or some group out to rule everything. Like a Blackbeard or Rocks. And Luffy will counter it by showing the power of unity and freedom and break the cycle.
I also think the only way Luffy is going to defeat Im is bringing together eight groups of people either eight races, pirates, organizations, and/or countries. This is a reference that there are multiple symbols in the series of the Kozuki, Alabasta, and Skypiean have the circle with the eight surrounding circles.
*Theory by Mr_Mythy