Over lunch recently, my colleagues and I were discussing the term "hardcore," and speculating on its origin. Our speculations evolved into "What has either a hard or soft core, where the hard cored thing would be used by professionals and the soft cored one by amateurs?" because this is where we figured the terms originated.
material such as stones and broken bricks used as the foundation for buildings, roads etc.
rather than having to do with a fruit or ball as our lunch group had envisioned. The foundation connotation is presumably the important connection between these usages.
However, looking into softcore has produced less satisfactory results. I found this description from 1875, which explains hard-core and soft-core and says that soft-core is essentially compostable garbage. What I don't understand is how this word came to be associated with its current, more familiar meaning, which is as a milder or watered down version of "hardcore."
Given their relationship, I expected there to be a more explicit connection between the two. For instance, that soft-core was a layer applied after hard-core or that inferior roads used soft-core instead of hard-core, but that doesn't seem to be the case. What is the connection here?