Typically this part is not necessary but it can be very useful when going through a lot of rocks/roots or over long distances with lots of debris. Even though the point opens a hole larger than the shafts in order to dramatically reduce friction there can be other factors that make it difficult to remove the shafts. As roots are split, rocks fractured, or gravel encountered, these can push back a bit against the larger diameter end of the shafts. Also resistance in pulling out the shafts can increase when connecting the shafts to rolls of poly water pipe, poly ethylene gas line or data conduit so that they can be pulled in as the shafts are being extracted. These are never straight. In these cases the extraction chain is extremely useful because it is attaches to the shafts and provides a secure connection between the shafts and another tool such as a leverage bar, digging bar, sliding sledge hammer or wench that can then be implemented to extract the shafts from the ground and pull in the conduit at the same time.
NOTE: Typically,when needed,the extraction chain is useful to extract the first shaft or two then the others will usually slide right out with little effort.
This is used to support the shafts and hold them up off of the ground...