The UX Matters course is for those who are responsible for the success of the product or make important decisions during the requirements collection and development phases. The prototype is just a tool. It helps visualize ideas related to the future product. Perhaps now you are not creating simple prototypes, but describing your thoughts with words only because it is easier to convey ideas in the usual way, but not always more effective.
Of course, the designer will help you visualize the ideas, if he correctly understood you and knows how to build the right user experience. And if you (or a stakeholder) have a question as to why the designer drew it this way, can you argue the decision?
Modern users are increasingly “eye-loving”. To improve the product, you need to know what to pay attention to and how to test interfaces, so working with UX will save you a lot of nerves, time and money.