Is Plagiarism Becoming Obsolete?
The reason why such things happen is, I think, pretty clear. Academic credentials are useful not only to academics but, for the status they bring, to lots of other people as well. To those other people—and, I suspect, to many academics—the requirements for getting those credentials are seen as obstacles not opportunities, a set of arbitrary hoops they are expected to jump through. There is a natural temptation to walk around the hoops and hope nobody is watching.
This may be an issue of vanishing importance, given the existence of the internet and search engines. The better our tools are for discovering plagiarism, the less the temptation to commit it. And in the limiting case—a world where anyone reading a (digital) document can in a few seconds check to see where every part of it came from—the norms that define plagiarism may gradually fade away. Nobody, after all, considers it plagiarism if someone quotes a well known line— "to be or not to be," "there's something rotten in the state of Denmark," "It was the best of times, it was the worst of times," without bothering to attribute it.
With sufficiently good tools, every line is well known, and attributions become unnecessary.