The months of R&D to create a workaround could simply be because the subset of motherboards which trigger this issue are doing something borderline/unexpected with their voltage management, and finding a workaround for that behaviour in CPU microcode is non-trivial. Not all motherboard models appear to trigger the fault, which suggests that motherboard behaviour is at least a contributing factor to the problem.
ploxiln|1 year ago
Towards the middle of the video it brings up some very interesting evidence, from online game server farms that use 13900 and 14900 variants for their high single-core performance for the cost, but with server-grade motherboards and chipsets that do not do any overclocking, and would be considered "conservative". But these environments show a very high statistical failure rate for these particular CPU models. This suggests that some high percentage of CPUs produced are affected, and it's long run-time over which the problem can develop, not just enthusiast/gamer motherboards pushing high power levels.