Why Ruby Class Methods Resist Refactoring

In a nutshell:

• Splitting a long method into sub methods is easier in instances since it is in classes. Since you must not save state in a class, you need to pass around context as a long chain of parameters again and again.
• If your public API has a single entry point, you can still have a class-level method that takes care of constructing the instance etc. So it's all win.