Grow by delegating
Most open source projects need more contributors, but sometimes the established maintainers drive new people away. I don’t mean by being overtly hostile, although that does happen. Instead they hoard responsibility.
So-called “drive by” contributions — where someone makes a single contribution and then leaves — don’t require responsibility. In fact, the person making the contribution does not want any responsibility. They want to make their contribution and move on. Long-term contributors — the people you need to attract and retain to make your project sustainable — need to have responsibility to feel a sense of ownership. Without that ownership, they don’t feel like they’re part of the group and they’ll drift away.
Responsibility hoarding isn’t the result of ill intent. It’s a combination of “I already know how to do this so it will get done faster/better if I do it” and “if I give away my responsibility, what will I do?” The latter is simple: something else. When I was a systems administrator, the common motto was “automate yourself out of a job.” In the vast majority of cases, you could only ever asymptotically approach that goal. What really happened when you automated work is that you were freed from mundane tasks so that you could work on bigger or more complex problems. When you delegate some of your responsibility to others, that frees you up to work on other problems, whatever those may be.
As for the “faster/better” argument, that’s true. But how will anyone else get faster or better until they’ve had the practice? If you’re the only person who can do a task, then you’re stuck with it forever. Either you keep doing it far beyond the time that it’s enjoyable or you stop doing it and it doesn’t get done. If that task is important, now your project has a problem. Let someone else do the task slowly and poorly. Help them get better. Now there are two people who can cover it. And maybe they’ll teach someone else.
None of this is to say that you should give away critical tasks to random people as soon as they show up. That’s a recipe for disaster. But the people who show an intent to stick around and learn need to have a sense of responsibility. They can’t just be drones assigned a particular task.