AVX512 is a special instruction set that lets the CPU process large chunks of data at once. Works well for doing the same thing repeatedly across a set of data. Things like processing a lot of pixels at once, or processing a lot of audio frames at once. Color correction, audio effects, etc. While image has been moving to the GPU, audio is still on CPU. So you see AVX a lot on audio. Apple seems pretty into AVX512, so my guess is Logic has a lot of AVX512 optimization.
If you wanted to do a gain boost on audio or something, that's a pretty basic acceleration case for AVX. A lot of audio filters are probably AVX accelerated. Especially on Mac where the Accelerate framework is built on AVX. AVX512 is the latest version, and Apple has been doing a lot of work with it.
The one place I've seen the Xeon easily beat Threadripper in benchmarks is on AVX workloads.
I don't know if that's enough to keep Apple on Intel. But it would be enough to give them pause if they thought they might be sacrificing Logic or FCPX performance by switching over.
I think the business and contract entanglements with Intel are more important. But for pro Mac apps, Threadripper is not a clear winner in all workflows.
Do you have any source for this claim?
My bet would be AVX optimisations in software like Logic bring only marginal gains that are easily offset by overall performance gain. Most of FCPX workload is offloaded to the GPU anyway would really surprise me if there were any recognisable differences in performance.