> Reviewing, testing and maintaining code takes up development time that could be used more productively. If there's something wrong with the PR (say, code style issues or mistakes) then you need to run through the cycle all over again.
OK, so your argument here is that maintainer doesn't want to create CI checks because it takes time and he knows the code style and doesn't need those.
> The project is open source in that you're free to use it, sell it and go through its code. Open source does not, however, imply that someone must put in the work for you if you want to apply changes to the code yourself.
But why close yourself to others? It is like throwing mic, or as if you would mark this thread as closed and no one would be allowed to comment - antisocial behavior.
You don't need to merge PRs, but come one, if you are a sole maintainer of a project, this project is not that big, and you for sure aren't getting that many PRs.
And also, one could consider PRs because you could find another person that understands your project goals and would be your co-maintainer.
Why such strange attitude here on HN? I found this place as very open and what I see in this thread praising of close-minded people.
Most projects seek contributors not alienate them.