> Any user with "interface administrator" status can change global JavaScript or CSS for all users on a given Wiki with no review.

True, but there aren't very many interface administrators. It looks like there are only 137 right now [0], which I agree is probably more than there should be, but that's still a relatively small number compared to the total number of active users. But there are lots of bots/duplicates in that list too, so the real number is likely quite a bit smaller. Plus, most of the users in that list are employed by Wikimedia, which presumably means that they're fairly well vetted.

[0]: https://en.wikipedia.org/w/api.php?action=query&format=json&...