To me the problem with this kind of explanations is that they miss the “why”. I understand “what” is currying and “how” to implement it. But I’m missing the “why”.

The real-world example doesn’t tell me why I would prefer currying instead of putting the date at the end and making it optional, then checking if missing to assign current date. And for the other argument I could create separate functions logDebug, logWarning and logError, those would call the generic function with fixed strings, right?