As a merchant and frequent shopper, I find it discouraging to see others rate an item poorly soley on the fact that they did not recieve it and blame the merchant. Granted, if the magicbox was suddenly derezzed and could not deliver an item then it's obviously the merchant's fault but that is not the case most of the time. I totally agree that under more "personal rules", if you did not recieve the item then you cannot realistically rate the item. You are rating the item, not the service. (Though when you do come in contact with the seller then you can realistically rate the customer service.) ... Get what I mean?
Unfortunately people do not read the "fine print" in a lot of shops stating that buyers should message the seller if there is a failed delivery due to SL hiccups and wholeheartedly believe that it is the seller's fault.