But adding a new server includes having to buy new licenses, which is a consideration you don't have with OSes that under licensing. It costs extra money, and used to be per socket when their infrastructure was conceived.
So what? Licenses are not expensive, especially compared to all of their other costs like the dozens of staff, and paying an invoice isn't complicated. They maintain their own hardware in colocation facilities so they'll get a new license way before they even get the hardware shipped out.
Why does this make scaling out "never an easy option for them"?