It is also super powerful technique when using the closure of a function as a way to encapsulate logic and state. A good example is this implementation of a json parser in js[1]. Attempt at lifting the lexer functions or state out of the function would result in every function needing to be wrapped with a factory function. Parser have always been tricky and before I knew this technique I would have reached for a parser combinator/generator but this is a very sensible way of doing it.

[1] https://lihautan.com/json-parser-with-javascript/