Simply put, if you can choose the place of delivery, it is equivalent to having the right of choice, and all the rights of choice are valuable. Therefore, the contracts owned by the short side are more valuable, which leads to more people shorting, which should depress the futures price.

Futures trading is a centralized trading form of standardized forward contracts. That is to say, the trading behavior that both parties buy and sell a certain quantity and quality of goods at a certain price at a certain time and place in the future by buying and selling futures contracts in the futures exchange according to the terms stipulated in the contract. The ultimate goal of futures trading is not the transfer of commodity ownership, but to avoid spot price risk by buying and selling futures contracts.