The human has unique context. They may work in a niche domain or they talked to people and observed an unsolved problem. Then they express a potential solution via OSS. It's like product sense. Then they share that with others who find it interesting. The code is a great way to encapsulate the idea. It is usually the result of research and back and forth not a single prompt. It would be way harder to think through or build a solution without AI even if they had context.