I wonder what happens when sites start using techniques like Zip/Compression bombs to defend against impolite mass downloaders. Particularly, in this case of downloading images without honoring robots.txt, a PNG/JPEG/ZIP bomb [1] might be a countermeasure in this arms race. [1]: https://www.bamsoftware.com/hacks/deflate.html
I appreciate the idea, but it's also a border line crime if you end up bringing down the requester (not that I would shed any tears).
WARNING
This PNG image is an example of a compressed image file that might expand to a huge size upon decompression. PLEASE DO NOT DOWNLOAD IT. We are not responsible for consequences if you do not follow this instruction.
and someone does that anyways, they are to blame, aren't they?
Especially downloaders who claim they are entitled to download it and hosters must use their proprietary opt-out scheme (like the ones on the original linked article) should also learn that they should follow the hoster's instruction and NOT download the zip bomb.
(And the hoster also lists that specific file in robots.txt)