Actually, the whole X3D cache is a Epyc cutdown.
View: https://www.youtube.com/watch?v=7H4eg2jOvVw
X3D came from high end customers who needed chips with higher amounts of cache instead of cores or just speed. AMD designed certain line of EYYC's with additional cache as we're seeing in the X3D.
Some EPYC chips did not make it, AMD hardware engineering team had to come up if the additional cache would be helpful in certain things. So the X3D was born since the extra cache helps games a lot.
There's no benefit other then a fat flat super expensive chip for no reason, with a absurd power requirement if you would slap 8X the amount of cache onto a chip like that. Due to CCD's having to communicate with one and another the latency involved would kind of destroy the purpose of the X3D in the first place.
Stop idolizing about a Dual CCD X3D chip - they have internally tested that and came up with, there's barely any benefit.