A machine requirements check would be useful, but I can't think of many companies that would implement something that results in less sales. What's the upside?

A machine requirements check would be useful, but I can't think of many companies that would implement something that results in less sales. What's the upside? Maybe some good will? I'm not saying valve wants people to buy games they can't run or anything like that, but it would be an expensive ongoing effort to make less money.