These shaders are for people to use without needing to understand any of the logic of the shaders or mess with them. Just change displacement settings, and PF seeds or settings, etc, as if it was a complete shader itself.
The simple shape is simple, nothing special, it's what you can do with it. Similar to my voronoi displacement shader or my faux strata, almost infinite possibility without diving into what shader is actually using what feature, or plugging new nodes, etc.
If I was just doing simple perlin or sin, I'd just do that. But this is meant to be flexible without all the recreation of node networks in new scenes. If you look closely, the function is very simple. It's just been set up in a way to expose settings so there are no confusing transform shaders and colour adjusts you have to search for or be aware of to know what they're doing. It's all named out, categorized, and organized.