Presumably because it's a real life workload that is more relevant to consumers and easier to understand.
But benchmarks where one hardware has to do much more work than the other is obviously not fit to determine the actual performance differences between hardware; and that is exactly what the article we're commenting on is doing.
People aren't concerned about the hardware itself. They're concerned about what it can do. If circumstances mean that your powerful hardware can't be utilized, then the powerful hardware is just extra cost and no benefit.