It's better to ask theymos. In case of signatures, there no direct theft. After my theft are you forbidden to keep using it or what?

Or if we will think in such way, will it be proper decision to ban you from here, if the "owner" of this thought about "plagiarism is theft" (or at least his children, don't forget - 70 years after death copyright works) will appear here and ask us to do it? Or if the owner (what it's better fit here) of this thought - "Plagiarism is against rules because the person who plagiarize benefits from what copied and pasted without any effort. Plagiarism is against rules because it's kind of theft, not because of spamming." (i even see exactly the same idea but in other words here from another user) will ask us to ban you for plagiarism and theft.