The weight of the rake and the curve of the tines are enough to dig in and pull dirt ... loose dirt.
The advantage here is that if the nose of the tractor rises, it won't force the rake tines down like will happen with a rigid top link.
My yard is horribly uneven and off level. After I did some digging and had some fill dropped, I went to work with the rake. After the first few passes with a rigid top link, it was almost worse than before I started. As the nose rose and fell, so did the rake, digging in and leaving high spots of loose fill.
Switched to a chain and the difference was noticeable on the first pass. Yes, it took quite a few passes to get it anywhere near smooth, but it was clear that wouldn't have happened at all without the chain.