The author deliberately did not draw,,, there is no reason for this, it is just an expression technique of painting, people want to express it this way, there are not so many reasons. . . Look at the hands of some cartoon characters. They have four fingers and one is omitted. That's how it's expressed, it doesn't have to be realistic. Some cartoons also deliberately exaggerate the facial features, some draw the eyes very large, and some deliberately draw the lips into a donut shape. . . It's just a way of expression. The author likes to portray it this way, that's it.