This requires javascript to work as it requires a page scroll to trigger the hash.
As far as I remember it also disabled the wp-comments.php directly, if you test the plugin disable JavaScript in the browser and try to hit wp-comments.php you won’t succeed. Most spambot is keeping the CPU cost down and don’t render JavaScript I guess. So it won’t work at all for them, real users run JavaScript in their browser where this function and hash can be triggered.
So it won’t require JavaScript to run and trigger the hash as it blocks wp-comments.php as it doesn’t have the hash, and it will not be many false positive as most users have JavaScript, meaning the hash will be generated and work for real users. If it didn’t block wp-comments.php it wouldn’t be ideal as mentioned most spambots don’t spend computing power on firing JavaScript to send comment spam.
It would be nice to have, the problem I see is that you inherit wp core comments in general. Sites which have normal comments and site reviews would not be able to utilize the site reviews spam blocker in native comments fields on other posts. While it would require using above-mentioned plugin to sort that. If site reviews can’t have an extra check box after enable, “enable for native comments as well”. To reduce duplicated functions which can conflict. Maybe before this feature, you can make sure site reviews is compatible with above-mentioned plugin?
