In my experience success in a project isn't about the amount of code that can be produced, it's more about the thoughtfulness behind features and fixes. A lot of the work going into reviewing pull requests is understanding it in the context of the project's broader goals.

This gets a lot harder when there is a giant wall of text that the pull requester doesn't understand and can't really discuss outside of asking AI (and probably getting "The reviewer is right to push back - I was too aggressive in my blah blah blah" as an answer).

A lot of (but maybe not all) pull requests are fundamentally a human to human task, even if there is a lot of technical details involved.

Part of this is an argument for size limits on PRs.

Another part is "how do we communicate project goals and ideals and standards?" The answer to that, I'd argue, is not simple, and will inherently run into scale issues. It's something that needs to be tackled as you move from a bespoke craft project to an industrial project.

Now, maybe you never move. It's okay and good for hobby projects to exist. But let's be clear about the choice there.