The simplest explanation I can come up with is: Without a job system, those threads would do nothing for most of the time and then you'd have to sync them with the main thread anyway. A waste of 2 threads, really. A decent job system ( assuming unity is using a fibre-like system underneath ) can really put 'dem cores to work. The end result is: The user-facing part of the job system will make it easier for gameplay programmers to parallelize their own stuff. And it will do so very efficiently.