The old computers had multiple cards inside including video cards, large CPUs with full sized boards, HDs made of solid aluminum, circuit boards on the CDROM and/or DVD drive etc plus RAM sticks. New machines have small boards with everything built in so no cards, possible small SSD drives nobody wants, and the optical drive is like a laptop drive worthless. The supply of older machines must be out of the recycling stream bu now (in any appreciable quantity anyway). Servers are the last gasp in recycling profit wise and there will be less and less of those with 64 core chips coming out hosting many virtual machines in 1 server.



Referbing machines isn't as profitable since new machines got so cheap and people tend to want laptops over desktops anyway. Finding large working hard drives also cuts into profits and SSD's will lose you money if you have to buy them. So ewaste people need massive quantities of material or don't bother.