There is not a meaningful semantic difference between what you're describing and what tools like rayon provide (and BTW, threads do just fine when pinned to a c

There is not a meaningful semantic difference between what you're describing and what tools like rayon provide (and BTW, threads do just fine when pinned to a core and appropriately managed as they should be in large data processing workloads). Whether threads are used on the backend is largely a distraction, you still have to write things roughly the same way to create correct code (for example, you cannot share memory between tasks on different cores, or on different nodes, without synchronizing somehow).