Why can't pc games be traded in ?

[H3RBSKI]

I know this is basically linked to the cd key, but what's stopping say steam from allowing you to trade the game against another game and then they block your cd and remove your install?
I have so many games on steam that I have played for a few hours and got bored. If I were on my ps3 I would have just took it back.
Never really understood why this cant be done on a pc. Somebody enlighten me?

 

[H3RBSKI]

I just find it annoying as I have so many games that I never play but there are several games I'd love to play. But instead of being able to get rid of the ones I don't play I have to pay full price for them or wait until there is a decent sale on. I've noticed gmg allow you to trade in but there is a very limited choice in what you can trade as most of their stuff uses steam.

 

[H3RBSKI]

Not anything physical. The 2nd hand and the new one are identical in every way. There's zero incentive to buy new.

But they wouldn't need to sell it back on pre owned. It's a digital download so they can sell back on at full price but allow you to trade it back to them for discounts on other games