Another popular rationalization is that starting with a clean slate will magically result in a product so superior that the world will beat the proverbial path to the company's door. Not in all cases, but certainly in many, these arguments are specious and self-delusional. History is absolutely clear that in a high percentage of cases, companies would have been further ahead using an existing design. In only a few cases can a company look back and really justify the additional effort it took to design a new architecture, processor, or core. Surely some unidentified force is at work that causes companies to repeatedly overestimate what they can achieve by starting anew and chronically underestimate the costs of doing so.
History is replete with examples of such miscalculations.
Probably the most blatant case is that of RISC architecture. In the late 1980s, when RISC made its debut, it appeared to offer huge advantages over existing CISC architecture. Proponents, mistakenly it turns out, thought they could exploit these advantages to displace entrenched CISCs in computers. Obviously, RISC backers overestimated the potential of their technology and underestimated both the size of the software hurdle and the progress that would be made by CISC competitors. In a huge miscalculation, RISC proponents badly underestimated the impact of exponential growth in transistor budget, which rendered one of RISC's most touted advantages, transistor efficiency, all but moot.