It wouldn’t be the solution on it’s own. It would be more of a “huge rivers start from small streams” kind of solution. Or more like part of a solution.
And I bet gold sellers aren’t currently even close to getting their business profitable. There seems to be harsh competition among different gold sellers to gain their possible customer base on this game. Even if they were to use stolen credit cards or something similar, using those credit cards is still an expense for them. The cards aren’t infinite either. Part of their money might also come from other games where they already have their services up and running, so it’s more of a risk investment for them on this game during the EA. They are trying to get a head start to other gold sellers.
There’s no way they can keep up investing this much resources on this game for months. All IMC has to do is to get them under control in the long run.