Pheace: This argument would seem particularly suited to a forum like GOG where people who argue consumer rights a lot (particularly but not exclusive to DRM-free) tend to gather. Yet this particular discussion generally doesn't seem to get much traction on these forums.
So you mean to say that you never claimed there is a contradiction with not liking DRM and not demanding resales/trading of used GOG (=DRM-free) games, but that you feel people who don't like DRM should logically also demand resales/trading of used GOG (=DRM-free) games?
I still fail to see why such second-hand sales demands would fit especially well in GOG. It is quite the opposite actually, read below. (Yet, I do recall quite many people also in GOG forums demanding just that, ie. all digital items (DRM-free games included) should be tradeable and resellable goods).
Pheace: In simpler terms. I'm surprised a group of people who regularly passionately defend consumer rights don't seem to particularly do so for this one.
Maybe these people understand that in order for reselling and trading of digital items to work in practise, there would have to be stringent DRM. In simpler terms, second-hand market/trading and DRM-free don't sit well together.
On the other hand, on sites like Steam where there indeed is DRM to control who plays what and when, a trading or reselling system could be easily created. so it is more understandable such arguments are made in Steam forums. Doesn't greenmangaming.com have something like that already?