Everyone in the entire chain. From artist to venue to promoter/booker to ticket platform. None of them want to refund. Not just for the obvious, but they make a killing selling ticket insurance.
Then scalpers have zero risk if they overbuy, encouraging scalpers even more.
If you restrict refunds to be permissible only until a certain point before the event, that will create a window in which unsuccessfully scalped tickets are released back into the pool for general public, bypassing scalpers. If scalpers choose to hold onto the tickets beyond the point, they wouldn't really be able to liquidate. I'd say that we shouldn't let perfect be the enemy of good, with regards to refunds.