In general, material cited or conciously taken from others' work has to be attributed properly. It might not be always possible to catch people not doing it, but some cases are more clear than others (for instance if publishing-ready graphics are used without attribution, or screenshots of PDFs). We have to trust users to know best what parts they have to give attribution for, but I think it is fair and even our "duty" to ask when there is doubt, in order to keep the standard as high as possible.
Tl;dr: In the cited case, consider my comments a (soft) moderation measure.
In that particular case, I have made the following observations.
- A person has been creating a multitude of accounts, all with closed and downvoted question of the same style.
- Those questions are extremely homework-dumpish.
- The person does not seem to digest the answers or hints at all.
I also managed to figure out where the questions came from, and they are indeed copied from exercise sheets of an undergraduate TCS course. Therefore, I reasoned that
- the person tries to cheat and
- the person abuses our site.
As our methods of dealing with this are limited (in particular I would not expect suspensions to be effective) and former attempts to convince the person to change their behaviour failed, I decided to expose the person's misbehaviour by linking to the exercise sheets and annotating them with their due date, demonstrating that the person is trying to get us to do their homework in an objective way. I hope that other members of the site see this information and draw their own conclusions -- I can't force anyone to not help this person cheat.
Note that the person told me of their university affiliation in an email to me (to my private address!) and the exercise sheets are available publicly, so I am neither abusing my position nor disclosing private information.