The danger of these rules was not just that they created land mines for the unwary, but that their elaborateness made them an effective substitute for virtue.

The problem indeed is not that some very thorny bushes exist in a human habitat (they are often quite useful, and normally a nuisance at worst), but the aggressive expansion of growth, often mutating.

This seems to be a noticeably Protestant-specific effect.

The quoted paragraph stands on two hidden premises:

1. The rules in question are dynamic, i.e. prig-dom equals “morally fashionable”. Otherwise nobody is unwary, everyone knows to steer clear. The minefield is not only well marked, but has stable beaten paths circumventing it. Some are even paved.

2. The elaborateness is not mitigated, which generally also points to both dynamic and over-emphasized nature of said rules. Otherwise, humans adapt. On both sides.
Note that in a people without a dynamic moral fashion, i.e. traditional, either

A. (2) is true, in which case the society in question self-insulates until either everyone is tired of this nonsense or it gets quite inbred and then swept aside by someone else, or

B. neither is true: the people just learned to accept that the rules have subsets and gradations, so the monks are of course, very holy, but the townies and the rustics can’t be expected to act the same way, and the foreigners are, well, foreigners.

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Response on Gray Mirror: “Paul Graham’s error” https://graymirror.substack.com/p/paul-grahams-error