Look, I'm not defending it. I don't really buy used because I've found you can buy new if you wait/shop around. I don't like the fact that selling would be difficult, but truth be told I don't have to purchase these systems.
I agree, but I think you're understating how established these platforms are and how un-free these supposedly free markets are.
As an example, do you remember when, about two years ago now, Microsoft
raised prices on XBL even as competition in the online gaming space grew more fierce, and services like PSN and Steam were catching up to or even exceeding XBL in provided services?
How could Microsoft do this? Even more importantly, how could they get away with it? The answer is that this free market isn't as free as we'd all like to believe. Microsoft is aware that many customers are stuck on their platform in a way that will be difficult to pull out from. If I wanted to switch from Xbox 360 to (for example) PC, that transition is not especially easy. If I want to keep playing the games I own, I will need to rebuy all of them over again. If I want to keep playing with the friends I've made, I'll need to convince all of them to move with me
en masse over to the PC so we can stay together. I may even need to buy a whole new PC if my current one does not play the games I want.
Many of these same basic concepts still apply today. While this is an easier time to switch platforms than it is mid-generation, it is still true that most of my friends would likely be on XBL. It's true that my gamerscore (or trophy list) will be reduced to zero. This isn't a completely free market where consumers can readily and easily switch between producers at little or no cost to themselves.