I would maybe agree with you if the marketplace were not operated by Valve. But it is. This makes very clear that the one of the intended use cases of the skins

I would maybe agree with you if the marketplace were not operated by Valve. But it is. This makes very clear that the one of the intended use cases of the skins is to be sold. Which is understandable, it's very likely Valves makes in the order of a billion dollars just from the marketplace.