I can't read Russian, and so don't understand the reference link for the flag. Nor do I necessarily think that because someone is selling merits necessarily means that a person is at risk of losing money by dealing with him. I think merit selling is a terrible practice, and I've tagged this moron for doing (or attempting to do) so--but I'm not supporting the flag.
buying merits is actually buying reputation. If the user has a fake reputation, there is a greater possibility of deceiving other members here. Of course, in the end, it usually ends in losing money. Merit seller here is not directly involved in fraud, but it is certainly a mediator in all.
Usually, we denote members who are promoting scam services, exchanges, ICO's etc... although they are only intermediaries in all.
however, I do not think we are doing any harm to the seller. Flag or just neg tag does not go directly to the profile that will send the merit.