I need a Python-based folder organizer that can efficiently sort files by their creation or modification date. The script should operate on a specified folder and logically organize files into date-based folders (e.g., YYYY-MM-DD). Flexibility to handle nested subfolders is something I may consider in the future, so ideally, the solution could be extended for that if needed. Focus on creating a simple and effective solution with clear, well-documented code. Present your approach and any relevant insights in your submission.