BoxCutter is a fully featured Boolean system more powerful than Booltool and Hard Ops combined however goes in a direction that is unique and different.
This is not an extension. This is a separate tool. Focused purely on cutting.
The features and workflows developed in Hard Ops are intended to streamline and speed up the hard surface workflow. Box Cutter is merely a concept of another idea that was just too big to be just a button in another plugin.