Answered my own question from their "Why Refurb" section:
When a Dell customer places an order, the company sends the order to an assembly line to be built, packaged and shipped. Technicians pick the necessary parts and send them to the assembly line, along with parts for the hundreds of other orders being fulfilled that day. If a customer changes or cancels their order, rather than bring the line to a stop, Dell finishes the build and sells the equipment at a discount. When this process happens, the machine is labeled refurbished.
This means that many of the refurbished machines sold by xByte Technologies are not just refurbished, they’ve never been in production. Often times with a refurbished server, you receive the benefit of never used equipment at a significant cost savings by taking advantage of the realities of made to order manufacturing.