Are updates the only disadvantage of denormalization?

I am trying to understand what are the disadvantages of denormalization. Say that I have the following database (School_has_Student is a denormalized table): I have read that the problems that you may face when using denormalization are related to the operations of INSERT, UPDATE, and DELETE. Now I understand why we have the UPDATE problem, because if I updated one piece of data, then I would have to update the rest of the related pieces of data (for example: if I updated the student name "Paul" in the Student table, then I would have to also update the student name "Paul" that exist two times in the School_has_Student table), but I don't understand why INSERT and DELETE are also problems. Note: I know that the increase of storage space is also a disadvantage, but I do not think it is a big disadvantage with current storage devices which have very large capacity.