Steam has changed its scam policy and will no longer restore items lost from a trade scam like it used to.
In the updated Scam FAQ Valve explains why they won’t be restoring items anymore.
Our community assigns an item a value that is at least partially determined by that item’s scarcity. If more copies of the item are added to the economy through inventory rollbacks, the value of every other instance of that item would be reduced. We sympathize with people who fall victim to scams, but we provide enough information on our website and within our trading system to help users make good trading decisions. All trade scams can be avoided.
While this won’t make scam victims happy, it will keep item value where is should be. It seems that Steam is making some policy changes this month like they did with its new refund policy.