" Nothing new under the sun" I don't know who came up with that phrase, but Col. Sherman T. Potter said it at least once
Having taught writing, and for a while at a small college, I realized most people have little to no idea how to cite or use proper documentation, and thus, often plagiarize (some have been taught to do so improperly at their high schools). And, albeit I think of him as a great politician, even Veep Biden plagiarized years ago. Of course the Trumpester fire doesn't care about plagiarism or flat out lying.
The very worst form of plagiarism is bubonic.
Once one person starts doing it, everyone around them starts doing it too.