Just to make sure, do you agree with the definition I alluded to in my comment (where "correct" means that market prices track intrinsic value, and "flawed" is anything else)?
In any case, we already know that there are cases where capitalism fails, the best-known probably being the monopoly. We even know that there are certain market conditions that encourage these failure modes (for example, economies of scale encourage monopolies and oligopolies). Recognizing another possible failure mode (non-collusive cartels) and the conditions that trigger it doesn't push capitalism over the line from desirable to flawed. Maybe you already believe that capitalism is flawed, but I don't think that this by itself pushes it over the line.
In any case, we already know that there are cases where capitalism fails, the best-known probably being the monopoly. We even know that there are certain market conditions that encourage these failure modes (for example, economies of scale encourage monopolies and oligopolies). Recognizing another possible failure mode (non-collusive cartels) and the conditions that trigger it doesn't push capitalism over the line from desirable to flawed. Maybe you already believe that capitalism is flawed, but I don't think that this by itself pushes it over the line.