"This works for me, but I need help understanding why, because maybe it would help others" is a legitimate position to be in--has been since long before LLMs. I think we miss out on something when we ignore that position.
I'm not saying that anybody should be obligated to review large volumes of low confidence code... just that we should not make policies that ignore shades of gray which, with some collaboration, could bear fruit.
The change with this justification absolutely exists and has existed for a long time, but this justification only works for small changes (in the past and still today). Don’t come to me with a huge refactor or new feature and this explanation, which is happening more and more recently (it’s an easy strawman to make and hard to prove, but I certainly see it in practice).
I think the key thing you are missing here is that most successful open source maintainers don’t lack expertise, they lack time. They are generally capable of improving their projects in any direction they want without help. Mentoring new contributors is basically always a loss in the short term as far as the maintainer is concerned. The project does get improved, but it generally takes longer than if they did it by themselves from scratch, and the improvements might be in an area they don’t much care about. The payoff for the maintainers only ever happened in the long term if the mentorship succeeded and they get a viable independent long term contributor.