You've constructed a false dichotomy. There is a spectrum from 0-%100 adherence with the HIG and all the other rules. While the reviewers do not require %100

You've constructed a false dichotomy. There is a spectrum from 0-%100 adherence with the HIG and all the other rules. While the reviewers do not require %100 conformity, that does not mean there is "no consistent standard" or that its "completely arbitrary". In my experience reviewers are very careful to be precise and document, including screenshots, the specifics that cause a rejection. Having been rejected, none of them were arbitrary. Were you ever rejected?