When I was learning to program in C/C++ from different sources, it was common to review and analyze code that was simplified with shortcuts. It was suitable for practical application, but shortcuts would make coding very difficult to train to students. This technique should be 100% avoided during training. I would spend hours refactoring this code to make it understandable for my students.
Shortcuts are very useful once you have a module completed. Then, your objective would be to streamline the code so that it implements cleaner and compile faster.
A separate module should be set aside for training new coders how to streamline code using the arrow function. During training, ordinary functions should be declared separately and used so that the student can understand the concepts and trace the procedure properly.