Are dog leashes good?

I'm curious to know, are dog leashes actually beneficial for both dogs and their owners? Do they provide a sense of control and safety for both parties involved, or could they potentially lead to discomfort or even injury? Additionally, are there any alternative methods to training and managing dogs that could be just as effective, if not more so? I'm eager to learn more about the pros and cons of using dog leashes and what the best practices are for ensuring a positive experience for both dogs and their humans.