In the epilogue of the book, it's suggested that Particicution was intended as a release for the Handmaids, to give them the satisfaction of tearing a man apart with their bare hands.
The show handles the Handmaids' role in executions differently. With hangings, for example, in the book, the Handmaids touch a length of rope as a symbolic participation in the hanging. On the show, they are doing the work when the Marthas are executed, physically pulling the ropes to open the trapdoors. I would say that, in the show, having the Handmaids participate in executions is a combination of framing