PNV - Banter and General Comments, page-11592

You can short all those things if you find someone willing to lend you, there's nothing stopping you from doing it though. Shorting is just inherently easier when it comes to shares given how liquid the market is, those other markets aren't very liquid and borrowing costs would be quite high as well. There's also not much variation in prices when it comes to those things either

Do you really won't the stock market to be as illiquid as those markets? You can't simply buy or sell a house at a moments notice, the reasons why we can buy and sell shares whenever we want is because of things like shorting which provide liquidity