Because when you know it’s blacklisted you might try with a different IP, whereas if you don’t you will just wait (forever).

Imagine we wouldn't tell criminals the law because they might try to find holes... This is just user-hostile and security through obscurity. If someone on HN knows that this is what is shown to banned people then so will the people that scrape or mean harm to imgur

In a world where we couldn't arrest criminals, only keep track of them in a log book, yeah that's probably exactly what we'd do

There’s no law here, just someone trying to protect their website.