It helps us to understand and to memorize. Classification coupled to inheritance offers to developers the advantage not to have to develop methods for different similar objects. We must be aware that the principle of classification and of inheritance are only principles created by our mind. Inheritance decreases the amount of work, but increases the complexity. For the books at home or for a single exemplar, a classification or inheritance doesn't exist.
Objects are independent elements.
Similar objects may have to be processed in a same way. However, it would oblige the developer to think to the consequences of the modification for each different kind of object. This is an opportunity to find errors. An other solution is to define information entities and processes. Then the processes are explicitely linked to their information entity or information entities.