Lu Xun's opposition to classical Chinese should be considered from the literary point of view, because classical Chinese is relatively rigid and basically cannot express rich emotions, while the sentence patterns of vernacular Chinese are relatively free. For example, the classical Chinese is called "Dad" and "Dad", and the vernacular is called "Dad".
For a person with a low level of knowledge, reading classical Chinese is very difficult, because he has to consider how to translate it into a language he can understand. Just as China people are to English, those who have studied English can know what an English sentence is at once, but for those who have not studied English, it is like a gobbledygook.