Comment by smallmancontrov

You can have that today. Just go out and buy more CPUs until they have enough cores to equal the number of SMs in your GPU (or memory bandwidth, or whatever). The problem is that the overhead of being general purpose -- prefetch, speculative execution, permissions, complex shared cache hierarchies, etc -- comes at a cost. I wish it was free, too. Everyone does. But it just isn't. If you have a workload that can jettison or amortize these costs due to being embarrassingly parallel, the winning strategy is to do so, and those workloads are common enough that we have hardware for column A and hardware for column B.