> The extra cache doesn't do a damn thing (maybe +2%)

It depends on the task. For some memory-bound tasks the extra cache is very helpful. For CFD and other simulation workloads the benefits are huge.

For other tasks it doesn't help at all.

If someone wants a simple gaming CPU or general purpose CPU they don't need to spend the money for this. They don't need the 16-core CPU at all. The 9850X3D is a better buy for most users who aren't frequently doing a lot of highly parallel work