It provides a temptation to students who are looking for exam answers and want to cheat in class. You also can’t track who is using Course Hero. Often, notes are posted anonymously, so the individual who posted them cannot be tracked down.
Course Hero isn’t really free. While you can create an account for no cost, you can’t view anything until you pay in one of two ways: By posting materials (40 documents = 1 month free) By paying a monthly, 6 month, or yearly fee.