I think their point is that computers used to defy inflation. Across the decades, computers were getting cheaper in an absolute sense (i.e. not factoring in inflation) and astonishingly cheaper in terms of dollars per unit of performance.

Even when the cost of the cheapest computers bottomed out, it likely had more to do with lower prices not making sense. At a certain point, the cost of things that encapsulate the computer and I/O (like the enclosure and screen) end up overwhelming the cost of the actual compute.