Answer: Because Spain's colonies were big and they had multiple, being hard to govern from a different continent.
Explanation: Since Spain's colonies are in the Americas, It is hard to govern these over sea territories, because Spain is in Europe, and its colonies are in the Americas. This distance is 7,097 km. That is not a lot, though carrying messages and other info can take a lot. This is why Spain's rulers set up a chain of command, which consisted of the king, viceroy, and governor.