Diagrams in UML notation
UML diagrams and the way they are used, since the very beginning of this notation, have aroused emotions and waves of conflicting comments. The reason for this is the high level of abstraction of the analysis stage and modelling as a discipline, and the fairly widespread misunderstanding of the essence of this notation. This is compounded by the huge difference between what we call analysis and object-oriented design (OOAD) and object-oriented programming languages (OOP).UML notation is mistakenly treated by many people as just another set of symbols for creating illustrations. Most developers I know feel that these diagrams do nothing to help them, and they are generally right, because the quality and content of much of the documentation produced with UML, is poor, and such documentation is actually useless to the software vendor.
Source: Diagramy w notacji UML – Jarosław Żeliński IT-Consulting