I'm not sure about people who are proficient in English. But as a person who isn't very good at it, I feel refreshed whenever I found images related to the content. It usually made me understand the message more quickly.
However, most of answers/questions in Stackexchange network (that I found) doesn't have embedded images in them. So I start to wonder if it's a bad practice for Q&A sites? What do you thing about people who include images/screenshots in their questions/answers?