While it would be nice to have a multi-threaded benchmark that demonstrates a realistic scaling towards many threads, I have no reason whatsoever to trust that the Geekbench implementers are capable to optimize the inter-thread communication well enough for reaching the limits imposed by the hardware.

If they use inefficient thread synchronization methods, like those offered by the C++ compiler, or by the pthreads library on Linux, or by some of the older Win32 functions, their results will be much too pessimistic for the CPUs with many cores, creating the wrong impression that they are not much better, or not better at all, than CPUs with less cores.

For Geekbench 6, I have seen enough results where CPUs that are much better for real multi-threaded workloads appeared to be almost the same as clearly inferior CPUs.

For multi-threaded benchmarks, if they are embarassingly parallel the quality of the implementation does not influence the results, but otherwise it is not possible to trust the results without having access not only to the source program of the benchmark, but also to the compilers used by it.

I have seen a lot of benchmarks of locking methods used for thread synchronization, where the results could not be interpreted correctly without seeing the assembly language instructions generated by the compiler for the locking sequences, because a bad assembly generation could matter more than the high-level algorithms whom the benchmark was supposed to compare.