This blog post[0] explains it pretty well: "Fewer and fewer computer users think their computer is too slow." And therefore they only buy new computer if the current one breaks. "This happens less and less often. Even most disk drives, which are about the most mechanical part of a computer system, come with at least a 3 year warranty."

"It means that computer purchasing decisions are no longer made based on price/performance or just performance, like in the dark ages. Now, when somebody decides to buy a new computer it will be price alone, or maybe price and service, that determines which computer to buy."

[0] https://jlforrest.wordpress.com/2015/12/18/the-forrest-curve...