Concurrency is not "single core parallelism". Concurrency describes tasks/threads of execution making independent progress of each other. Parallelism describes tasks/threads actually running at the same time.
Of course it is. Concurrency gives the impression to the user that parallel processing is being done, even when it's not. That's why my parents old 386 could render a moving mouse cursor and a progress bar at the same time (usually).
Concurrency lets you do things "in parallel" even if you can't actually do them in parallel.
