I can assure you that is Not the case with HN: on posting archive.is URL's, proof?
Look at my comment postings : https://news.ycombinator.com/threads?id=archo
Is it possible you have been shadow-banned for poor compliance to the [1]Guidelines & [2]FAQ's?
It's not banned in comments, but it is banned in submissions. @dang (HN's moderator) confirms that here: >>37130177
>Please submit the original source. If a post reports on something found on another site, submit the latter.
And explained on numerous occasions by dang.
For example, I've linked to my work, but it never occurred to me to use "Show HN".
Maybe this is no big deal? Or perhaps for new signups, it would be good to “soft force” them to read the FAQ?