I’m not sure what you mean by prioritizing. The Constitution sets up three co-equal branches of the American government. The legislative branch is responsible for making laws based on representative democracy. The judicial branch interprets those laws made by the legislative branch as applied to lawsuits and prosecutions. The executive branch wasn’t originally intended to have the sprawling power it now has. None of the myriad departments we now have been part of the vision of the founders. They are made up of unelected bureaucrats who wield regulatory power tantamount to law with no input from the citizenry. However, no branch can usurp the powers of the other. The executive branch can’t make law, the legislative branch can’t prosecute or try cases as the judicial branch and neither can tell the president what to do.
Those in favor of a divided government believe that such separations encourage more policing of those in power by the opposition, as well as limiting spending and the expansion of undesirable laws.