I\'m not very experienced with subjects such as Concurrency and Multithreading. In fact, in most of my web-development career I had never needed to touch these subjects.
Concurrency is basically being able to fork() processes and compute stuff in parallel the same way memory management is basically being able to call malloc. It is part of the story, but not all of it. Being able to simplify the issues relating to concurrency is the difference between languages that are good at concurrency and those that just can be concurrent.