Yes, it is a coincidence. Spanish colonies were initially geared towards resource extraction, which did well in places with wealthy, established civiliations already, or in places that had the proper climate for the cash crop of the day (sugar).

Bourbon Spain did eventually pursue more settler oriented colonies in places with more moderate climates (e.g. modern Argentina/Uruguay), but that came much later.

Side note: resource oriented colonies were viable in the colder climates as well. For example, France had colonies based on fur trading in very cold parts of North America. I don't know why Spain overlooked that type of colony, but perhaps they had their hands full with their other colonies to be concerned with that.

English-style settler colonies are really the odd man out in this time period, and it should also be noted that some of England's state driven ventures resembled resource extraction colonies more than settler colonies. Early Virginia is a notable example of a state-driven economic venture. Settler colonies were often driven by the migrants themselves, rather than the state...