The executive budget was a financial innovation designed to empower city mayors and city managers with the capacity to implement needed policy reforms in the Progressive Era. Since that time, the executive budget has become a tool by which the president of the United States has been able to substantively shape policy and draw power to the president from Congress, which was originally charged with "holding the purse"(and still is constitutionally, as there is no federal-legislative authority to change the constitution outside the amendment process or for congress to legislate away their authority). This has resulted in an ever increasing role and power base for what is now called the Office of Management and Budget.
In many respects, the budget process has become theatrical and artificial even while it remains highly politicized.