While having one language on the front end and back end might seem like less of a burden, the cognitive context for both of them are very different. Reasoning

While having one language on the front end and back end might seem like less of a burden, the cognitive context for both of them are very different. Reasoning about the backend feels much easier in languages like C# and even python. Because the majority of the code in the backend is about data storage, retrieval, data modeling, rich and complex business logic, etc. While on the front end, the focus is usually on data binding, immutable structures, etc. JS in react is fine and in my view, for the notion of same language everywhere, JS is a poor language.