Explain why some people in power want to limit or censor material being given to the people.

If they are a dictator, tyrant like joseph stalin, benito mussolini, and adolf hitler; they use the censorship of material method to leave people in ignorance as a method for them to keep ruling over them, because they are scared that as soon as they start reading intellectual books (one of the most censored tools in history by dictators) they could recollect knowledge and overthrow their totalitarian government (and it's completely their right)