Why wouldn’t oil or wheat or land or bonds work as money?
To understand why, think of simpler example: manufacturers money-off coupons. To anyone buying the product, the coupon is worth its face value. So why don’t coupons circulate as a kind of currency.
Let’s say you were planning on buying Charmin bath tissue today. Someone has a coupon for $1.00 off Charmin. It is worth nothing to him, because he isn’t buying the product. In theory, it “should” be worth $1.00 to you. But how much cash would you pay someone for that coupon?
Far less than $1.00.
With coupons, as with all non-monetary goods, the bid-ask spread is too wide for them to work as money.