The statement presented in your question is false. If a passage of writing does not have paragraphing cues, it will be harder to understand than one that does have such cues. Therefore, a lack of cues does make reading harder and the statement in your question is false.
Paragraph cues make it easier for a reader to follow the argument that a writer is making. They tell the reader how the paragraph that is just beginning relates to the previous paragraph. This alerts the reader to what the writer is trying to do. For example, if a paragraph is meant to contrast with the previous paragraph or to call that paragraph into question, it will be helpful to start the paragraph with something like “however” or “by contrast.” As soon as the reader sees this, they know that the current paragraph is going to make an argument that goes against the point made in the previous paragraph.
Without paragraphing cues like the ones in this example, it is harder to read a piece of writing and to determine what the writer is arguing. Please follow the link below for more examples of how this is so.