On the matter of why locking cells even matters, it’s all about maintaining the accuracy, reliability, and quality of the report. It prevents any incident of inaccurate data getting introduced into the report whether through accidental interactions or intentional sabotage. This is particularly important in cases where the report itself will play a role in the future of a large company. Even mistakes in the decimals can render a report disastrous for a corporation’s bottom line and an added zero is quite easy to overlook if the spreadsheet’s data set is already quite extensive.  Simply put, it is a means of protecting your sensitive report and the information that is held in it. If nothing else, it can help make sure that even you will not end up messing it up if you are not paying attention. After all, it does not take a malicious individual to make a report useless since it can just as easily be due to human error.