First, the site is not designed to do this and if you want to propose a feature along that line, you would need to ask a question on the general [StackExchange meta](http://meta.stackexchange.com/) site. I could migrate this question over there, but this would almost certainly be rejected and I think there is a worthwhile discussion in this topic that is specific to Serverfault.  

Personally, I don't think it's necessary at all (and I wouldn't be interested at all to triage questions into difficulty classes). You'll get your chance to contribute eventually and it's also OK to contribute another answer if you have something substantial to add that wasn't covered in earlier answers. Until then, the site is a great learning resource if you read a lot (highly voted) questions and answers as something will stick even if you don't need it immediately.  

Also, you don't need to limit yourself to questions that you can answer immediately. You can (should?) also look for question in tags that interest you that you think you could tackle if you invest a little bit of time, thought and google-fu into it. If you select good questions (if only there were more of these ...), this is excellent training for your own problem solving skills. You just have to be prepared to learn that very often, the amount of rep you gain for an answer is inversely proportional to the difficulty of the question and the effort you have to put into an answer.