You are totally right. I have done this plenty of times myself. It's one of the reasons I am short on equipment now, i gave away all but one of my manuals. This was meant more of something that Vapor4Life as a vender could do, not what we as individuals.
However, it could benefit this as well. By allowing people who may not have as many spares or any to get a hold of cheaper equipment to build kits to share. I can't think of many people who I know that would want my short purple autos, but if I had black ones they might be more willing to take them. I would gladly spend a bit to put together kits for my friends and co-workers but I only have so much to spend.
Sure if you know someone who can use it and have the equipment to spare its much better to share, but if you're one charger short and short on funds this might just be what you would need. The incentive of credit for gently used equipment would most likely increase the number of people contributing to this pool of equipment.