When they say that worn babies "cry less" they don't mean that they don't cry at all or that they are comforted simply by carrying and don't need any other needs met. They still need their other needs met just as much as other babies and will cry for it if they need to.
What they mean when they say that worn babies "cry less" usually means that baby is right there in your face, so you read your baby's signals before they have to work themselves up to a good cry. If baby is hungry and on your chest, they start rooting around before they start crying. A baby in a crib in another room, however, has to root around a long time in the crib before they finally work themselves up to get upset enough to cry. Then you hear them and go to them and by that time, they may have worked themselves up enough that it's difficult to calm them down enough again to get them to nurse. A baby that is farther away is simply more likely to get worked up and more difficult to calm down is most of it. When your baby is against you, you know and can meet their needs faster which generally makes them happier.
Some babies have issues that make them cry a lot, though, even if they are being worn, but wearing them can make all the difference in the world!