Blackstrap molasses health benefits were not a concern to our grand parents and great grandparents.  Much of the United States 150 years ago did not have access to sugar, at least not very often.  They learned to love the sweeteners that they had available locally; honey, maple syrup, other syrups, and blackstrap molasses.
Molassed did have to be shipped in but it was cheap and it did not go bad on long journeys.  Even the most remote mountain cabin generally had a supply of blackstrap ‘lasses.