Why not just make it yourself? It's just flour, water, and salt. It's far easier than yeast-based breads and easier than most quick breads, too. Two ingredient (self-rising flour and heavy cream) biscuits are about the only thing that's easier.
Maybe the flour is difficult to buy or most people don't have a way to dry the bread? Being on the ocean, St. John's is a pretty humid place.
Sure, you can probably find a way to achieve a "good enough" result with normal household appliances, especially when it doesn't actually need to be stored for years and you're just going to soak it again for some tranditional recipe.
But it's a lot more effort than most people want to invest when they just want to replicate that recipe.
The only real question is which kind of flour to use. I'm sure it ought to be whole wheat or a blend of whole wheat and white.