Perhaps because so many small project owners don't accept and merge in patches after people kindly submit pull requests containing proper patches. Albeit I see

Perhaps because so many small project owners don't accept and merge in patches after people kindly submit pull requests containing proper patches. Albeit I see this for many areas of open source, not just Rails, such as ObjectiveResource, Three20, and Moonshine. I've had to wait as long as 3 or 4 months before even getting some feedback from some project admins, and that's after an email or two. We shouldn't have to beg to get our patches committed. Some project owners are just lazy, or have a very narrow view of what they want to accept for patches. And that's fine, it's their project. But that's more the reason why people monkey patch and not continue to submit patches, of which they'd need to monkey patch anyway to have the change effective immediately. After all, the projects are often still active, and do update with bug fixes, etc. And if you've only modified the tree, then you need to reimplement after you update. A monkey patch avoids this requirement, letting you get on to more important work.