I have participated in the One Block/Month Swap and a Siggie Block swap on this Board and enjoyed both tremendously.
Guidelines were clearly stated regarding participation being open to ALL LEVELS of quilters. If you are not happy to chance receiving a block from a beginner that may be a little less than perfect, then don't participate.
Personally I found the challenge of working to someone else's criteria for a block an interesting way of moving outside my normal range and the friendships I made along the way have been an added bonus and a great pleasure.
Being international, the high cost of fabric and postage from my end does limit the frequency of my involvement in these swaps.