I'm not sure if Ross covered this exact topic, but definitely covered the topic of whether having games on a service like Steam, Origin, Uplay etc. would count as owning a game, when the game would become unplayable if Valve ever decided to remove Steam for whatever reason. Nothing lasts forever, and that's the issue here.
Selling games on Steam wouldn't be THAT far fetched considering Steam already has a firmly established second market where people can trade. I think it boils down to more of an issue with Valve being unwilling to let people actually have ownership over what they buy on Steam.
This is why I originally supported GOG as most of their games are DRM free. But with their Galaxy launcher now being a thing, it seems they are going the same route as Valve. As far as I know you can't resell games on any modern game distribution service.