But this rule does not work when there is a paraphrase.
I don't know whether that's true or not, but since paraphrasing is form of plagiarism it shouldn't be allowed. Thinking of it it may be even worse as that implies person knowing that he is actually cop[y/pasting but is trying to avoid being detected.
The only thing is that in some cases someone will not be banned for a case of plagiarism that is considered minor, that was a long time ago and that was only one time.
Then there is
this case where user plagiarized multiple times, and not long time ago.