The importance of AMD's use of chiplets should not be understated. Especially in the server space, it allows them to achieve far better yields on a monster L3 cache than Intel or any other competitor. Along with the modernized Zen UArch, this means they can achieve the same perf metrics at significantly lower cost than Intel.
Even more than yield issues I think that letting AMD better pool engineering effort between their desktop and server parts might have been really important. AMD is a smaller company than Intel and has to be clever about economizing.
