Because you are fooling yourself into thinking that you are learning a whole more than you are.
Most people tend to like teachers that explain in a way that make the subject feel easy, these are the types of instructors that get popular on youtube. Research in learning however may indicate that people learn much more when they are pushed to a point where they are uncomfortable, "good" explanations that don't force the students to figure out anything for themselves looks like they are especially detrimental. You can find quite a bit of research on the topic from a few of the keywords above.
People are in general not good at evaluating their own learning and tend to rank the teachers that make them feel comfortable, no the ones they learn the most from, as the best teachers.