I don't think Plagiarism is something that needs to be pointed out as being something you can't do. First of all, this is something that people should know they shouldn't do, for a number of reasons, and I believe most people who do this know it is wrong, but do it anyway.
Well it shouldn't have to be but it really does need to be pointed out that this isn't acceptable and you can see that from the number of threads from people in Meta asking why they were banned and if they can get a second chance, so people should be made aware of the rules and the punishments for doing this so there's no excuses then.
Also, I don't think it is as big of a problem in terms in the number of people getting into trouble doing this. Sure there are very many instances of this happening, however I suspect this is done by a fairly small number of people with a very large number of sockpuppet accounts, and I suspect this is often done via some kind of automation/AI.
The only change that has been made is that they now require one merit or purchase a Copper Membership but when some of the worst offenders are making tens to hundreds of thousands of dollars from abusing bounties and campaigns they'll just purchase the merit or rank to bypass this. Merits can then easily and quickly be distributed between their alts and that's why I think we should require much more merit before you can start earning here, or at least make them buy a much more expensive Silver or Gold rank.
Are the abusers buying the Copper memberships and getting banned? Most of the new Copper memberships I have seen appear to be bounty managers.
You'd have more of an idea about that than me - being able to see how many coppers get banned - I'm asking out of curiosity.