I did a project on the accuracy of a PC flight sim for a project at university. I'm not yet a commercial pilot (still in training) but have worked for a full flight simulator manufacturer as a software engineer.
I think the answer to your question is yes and no. In terms of flying the aircraft no pc flight sim can really help you very much. However what they can do is model operation of all the systems such as Autoflight, FMS, EICAS/ECAM etc. Whilst these used to be fairly crude the level of accuracy on some of the more recent 'add-ons' is extremely impressive.