When arguments are made in a vacuum, all kinds of nonsense can be justified. Take the argument that Big Pharma is conspiring to keep people sick because that way they will sell more products. I think there are two ways to argue against such an argument. The first is to show where it's wrong, that there are forces at play which invalidate such an argument. The second is to reject it until such times as there is evidence to support such an argument.
While the first route is a more tempting option, it's little more than an academic exercise. In the case of the medical dependence argument, I try to argue that there is competition and that if a product worked it would be better for a company to manufacture it because while it wouldn't have a continual income stream, it would have customers getting it on the sole basis that it worked. Second, in the case of medicine pretty much all we get has to undergo extensive testing for its efficacy. There are more reasons, but I think both of those are sufficient to defeat the argument.
But that's a fairly academic exercise. There's no reason to take the argument seriously to begin with. Even if the argument held, there would still be the problem that there's no evidence to support such a claim. It's wild speculation, and treating it as a serious idea only serves to validate nonsense. And worse than that, any crackpot who comes up with an argument could argue that they should be taken seriously just because they've strung a few words together in a somewhat coherent fashion. Sometimes it's better to just say "no" and put it to the person making the argument to make a case worthy of consideration.