Design of rock pile sites is incompatible with stone removal

A letter to the editor of the Providence Journal by a Pete Carlson includes:
"Cairns are quite common in Rhode Island, and the ones in Parker Woodland (that appear similar to the ones shown in the article) have been examined quite thoroughly with no conclusive explanation as to their purpose. We even have some on our property in Foster.

My theory is they are just piles of rocks. Over the last 300 years, local settlers, especially farmers, had to clear millions of tons of rocks from the land to make it suitable for tillage and pasture. Hidden in our re-grown forests are thousands of miles of stone walls and massive mounds of stones cleared from fields. Land not suited for crops was used as pasture and loose surface rocks were probably removed to expose more soil to grow more forage. What to do with the rocks? The simplest thing would be to just pile them up, ideally on a
big rock that would have been difficult to move. Those settlers who were careful would have made nice neat piles."

I see this as a sad lack of imagination and information. Let me quote from my comment to a previous post: "Here is someone who is a sloppy observer with no imagination. To be fair, the problem is perhaps that Mr. Carlson has not seen enough sites. Here are facts which he does not comprise. Sometimes rock piles are:
- well made
- from sorted rocks
- within larger patterns of piles
- at prominent locations on hills and by water.

Take your pick, any of that implies a design effort inconsistent with simply getting rid of rocks.