What a strangely uncivil response. I was trying to meet folks in the middle here and at least kindly suggest some attribution as a reply to some now (appreciably) deleted grumbling. I'm not trying to impress anyone by suggesting it, it's just the right thing to do if you can do it.
It's not necessarily the right thing to do. If creators don't leave any trace, especially in a community where sharing freely and without credit is commonplace, one shouldn't impose one's own moral lens.