Sarcasm?
Not particularly. I think there is certainly merit to trying to regulate certain types of sales, and punish those overstepping boundaries.
Someone buying/selling fake IDs or credit cards is a non-extreme example that comes to mind right away. Both may understand the consequences of the transaction should they be caught, however that doesn't mean that we should allow these transactions to take place here without leaving negative ratings and the like. IMO, thinking that these transactions should be allowed and go unpunished/unfiltered is a silly thing to think.
Unless I'm misunderstanding what you mean, in which case feel free to correct me.
The sale of fake IDs and stolen credit cards is illegal in most of the civilized world, so this is already against forum rules.
Further, both of your examples have real victims, and the harm is not that someone's feelings are hurt. There will be people and/or entities that will ultimately suffer real financial losses as a result of stolen credit cards and/or fake IDs.
There are not any *actual* victims of people selling forum accounts. None of the flawed arguments against account sales even make this claim. In fact these arguments fail to account for *real* market incentives not to do the very same things that those against account sales claim sales cause.
It is ridiculous to claim any kind of authority to regulate what people can and cannot do. Especially when you are in absolutely no way elected, and in no way accountable for your decisions. People who regulate others' actions who are neither elected nor accountable are generally described as "dictators".