Answer:
Some simple reasons for this could be that it is easier to manage spheres of influences that to manage a a system of colonies , and it is cheaper. The costs of running, occupying and defending colonies was high. You can get political, diplomatic subordination of weaker nations and trade and economic advantages in a spehere of influence, without having to occupy those countries militarily. This is a simple analysis maybe, but it seeks to highlight some pragmatic aspects.
Explanation:
