Allow me to put in my opinion here.
It certainly is not and should not be. As a morpher I am fuming whenever I see my work posted by people without any mention of me. But then I mostly ignore this, as long as the poster does not actively imply they were the creator of my morphs. I just keep a watchful eye on them. On the other side I mostly morph **29** pictures without their or their photographers' consent, and seldom any mention of them. This leads me to think I should be lenient towards those who don't know better. And perhaps you could be, too?
Of course we are all using images from internet, usual anonymous posted, and we often are not knowing the womans name and almost never photographers. So we can not often name them (but I usual do if I know). The case here we have different, a poster (lenay) uploads a morph in
forum for morphers, the image was posted on
this site
one day before and
still existes at time of his post, but he bothers not to name the morpher. So I could be pushed to criticise him because I could see enorm difference between that and the first case. And perhaps you could, too?