I too find irritating this practice of posting articles which have been taken from the press, but presented as if they were written for the Mudcat by a visitor. But I don't think integrity really comes into it. It just feels like bad manners. Bad manners to us here, and bad manners to the person who wrote the article.
I quite often come across articles which I feel shed some light on some issue, and I want to share them with people here who have been discussing the issue. So I will either put in a link to an article, with a brief quote to show what it is about, or maybe I might post the whole article. But it would never occur to me not to post in my own name in such a case, and give the impression that the person posting was the author.
I know that if I were the author of an article in a paper or magazine, and I heard that it had been posted in a form that suggested that I had done the posting myself,I would be very annoyed.