Well, there's a compelling argument. By the laws on the books, Valve is committing a crime by selling us a product that we don't own and can't re-sell. It's only because those consumer rights laws are older than digital distribution, combined with some confusing precedent over productivity software, that the laws don't clearly cover this scenario.
Please, don't give me the "license" baloney, that's been to court a long time ago, and it was ruled that a licensed copy is no different than any other physical good, and that there's no need for any type of permission from the original seller to re-sell such goods. Again, it's only the difference between a physical copy and a downloaded copy that allows them to circumvent First Sale Doctrine and other laws.
Someday, the plodding legal system will have to deal with digital ownership. Indeed, Valve has already been in court over these issues in Germany and the EU. They've updated the TOS to try and avoid class action lawsuits here is the US - they know this will be an issue at some point.
Until then, I'm sure they're glad you're blindly on their side.