The theory of calligraphy and painting is clear. Moreover, many people who paint Chinese paintings also practice calligraphy. Over time, they will also have a certain foundation in calligraphy.
This is not necessarily the case for those who study calligraphy. Many people only write but do not draw. The earliest person to practice the transition from calligraphy to painting was Zhao Mengfu of the Yuan Dynasty.
And the meaning of painting is relatively broad. Not only traditional Chinese painting is considered painting, but people who draw sketches, watercolors, and oil paintings may not necessarily learn calligraphy