Ah, yes and no. It’s the larger e-tailers and B&M that in fact have more ability to buy the entire tray directly from Intel or AMD. Intel and AMD aren’t going to ban selling tray CPUs at all, because if someone is willing to buy a whole tray, or in some instances a “half tray,” that’s a guaranteed large purchase. That’s also why there are practices such as tray discounts.
QuietPC either negotiated a tray purchase with AMD, or they bought from a system integrator who was working on a project for another company and had excess CPUs. For example, a tray purchase is 1,000 CPUs, but the integrator only needed 700. However tray discounts made more sense to purchase the entire tray rather than a half tray then trying to source the rest elsewhere. They now have 300 CPUs leftover, which they sell to QuietPC.
It was common in years past for B&M like Fry’s (they direct bought from Intel/AMD) and local shops (via suppliers) to sell tray CPUs. Newegg, B&H, and various other e-tailers also sold tray CPUs. However this is a leftover of bygone days when a local shop would build the PC and self-warranty it. It just became too much of a hassle for shops to deal with self-warranting tray CPUs. Even with a 30-day self warranty there’s going to be customers who scam or accidentally broke the product. It’s just easier to sell a box CPU and tell the customer “deal with the manufacturer warranty.”