Adding user profiles and rating systems will increase the perceived credibility of community information.
But does it increase the accuracy of the information? i.e. is it actually more credible or does it just appear to be better information?
In some cases it's both.
Question and answer sites like Yahoo Answers, Quora, and StackExchange do well here.
Usually, it's just the latter. The longest answers, the best written answers, or simply those from people with expertise in an entirely different field are voted the most accurate.
Improving the accuracy of information requires not that everyone be allowed to vote on how good they think it is, but that everyone with any relevant information on the topic contributes that information. This is in then aggregated (e.g. Wikipedia) to give more accurate results.
If user profiles and rating systems encourage everyone with a relevant field of expertise to share whatever they know on that topic, then they increase accuracy.
You can add user profiles and rating systems. You would get more accurate information if you can convince members they have unique insight on an issue, explain their contributions would make a direct impact on the community, and establish ground rules for the submitting information.