What is the conspiracy against Spain described by Gregory Ciero in his article "Were the Spaniards That Cruel?"

The article "Were the Spanish That Cruel?" by Gregory Cerio tells of a supposed conspiracy by other European nations against Spain that the Spanish refer to as "the Black Legend." According to Cerio, Spanish people received the reputation of being horribly avaricious and savage, not because they were any more brutal in their treatment of Native Americans in the New World but because other Europeans hated them for their success and prosperity.
Cerio claims that this was all part of a propaganda campaign to make the Spanish appear corrupt, cruel, and barbaric. He uses selected historical studies and quotations to prove that Northern Europeans were far more malevolent than Spaniards in their treatment of Native Americans and that the Spaniards were benign in comparison to other European powers.
In fact, the historical record shows that the Spanish were indeed cruel and barbaric in their treatment of Native Americans, starting with Christopher Columbus—who was an Italian but led the first Spanish expeditions to the New World. Columbus took native slaves with impunity and was so cruel that his governance and that of his brothers incited rebellion in the colonies. He was eventually returned to Spain in chains and imprisoned.
The Spanish conquistadors Cortez and Pizarro used deception to capture the rulers of the Aztecs and the Incas, ruthlessly slaughtered many of their people, and then plundered their empires for gold and other valuables. The encomienda system of slave labor that the Spanish instituted was one of the main factors in the near-extermination of native populations. It was eventually abolished due to its ongoing atrocities.
Cerio claims that Spanish monarchs instituted humane policies towards Native Americans. However, these same monarchs continued to send mercenaries and politicians to the Americas who ignored these policies and abused the native peoples. As mentioned above, Cerio also makes the argument that other Europeans mistreated Native American populations. It is not valid justification for inhumanly brutal behavior, though, to claim that others are doing it too.
In summary, although the Black Legend may have originated as a propaganda campaign against Spanish intentions in the New World, its existence does not justify the way that the Spanish (for the most part) severely mistreated native populations.
http://www.bbc.co.uk/history/british/tudors/conquistadors_01.shtml

https://www.britannica.com/topic/encomienda

https://www.history.com/topics/exploration/christopher-columbus