Open Source is a great way to share your hobbies and other contributions. Many businesses use Open Source products and many people like to contribute to Open Source projects.
Signing the Ethical Collaboration Community Agreement or some other NDA may not directly affect you or your project, but it does protect other people in your community. They might have a business need to protect their IP, like if they work for a company who has some product that they want to keep quiet before their launch.
You might not think there is a personal benefit from signing the Ethical Collaboration Community Agreement because you want everything to be Open Source. But you don’t want someone hearing about your project then running out to get a patent on your latest Open Source idea, do you? The Ethical Collaboration Community Agreement protects you – even as an Open Source advocate – from people “helping” you then turning around and doing something bad.
Part of the Ethical Collaboration Community Agreement is that ideas are transferred to the project owner on the project owner’s terms. So if you get some help from someone else, you can be assured that you won’t have trouble as you commit your project to the public through Open Source.