There is a like a billion economical reasons why shouldnt governments do that but the simplest reason would be that there would be a whole lot more cash in the market and the more cash there are in the World means the less it will worth.
Say you have 1 apple and you are hungry and someone came in and said he will give you 10 dollars for your apple, you would refuse it because you are hungry and you need it but if you have 1000 apples and hungry and someone says he would pay 10 dollars per apple you would sell like 990 of them.
Meaning the more cash there is , the less worthy it will have.