Some big projects have so many people trying to do PRs that it's actually a bit of a hassle to deal with them all. So I don't think maximising the number of contributors should necessarily be one of the top goals for projects that are already big or have guaranteed relevance.
Is learning a language even a thing anymore with $Internal_or_external_LLM_helper plugin available for every IDE? I haven't found syntax lookups to be that much a concern anymore and any boneheaded LLM suggestions are trivial to detect/fix.