Plastic bottle construction

My cousin recently sent me this page on constructing with soil-filled plastic bottles. I had seen similar things before based on stuffing plastic bottles with plastic garbage, but it seemed excessively labor-intensive to me. This soil-filling idea could solve that if one had an organized system for funneling sand or dirt into bottles, but if you're doing that and mortaring them together, why not just form adobe blocks or cob walls, which save you the effort of filling bottles? Either way, it's an interesting aesthetic, and a good way to divert some flow of plastic to our landfills, incinerators, and oceans.