I seems the intent of the Constitution is to keep the discrecionary power to spend money in the hands of the people. By giving agencies a “blank check” that is off the people’s annual appropriation books is a deceptive financial practice that borders on money laundering. Why did the Congress need to do this? Answer: The have allocated power to the administrative state that exceeds the intent of the Constitution.
Simple answer: They are too lazy and often too stupid to do their jobs, plus they are almost all grifters beholden to their moneybag "donors."