Well the space shuttle uses tech from 2002. 
https://qz.com/317406/why-nasas-newe…hip-from-2002/
Since most hair solutions are based on some form of shader technology something so old would seem to me a better fit with the UE4 engine as it has it’s own shader support so maybe Epic only need the framework technology with out having to pay for the shader technoligy.
buying into tech these days is like going to the hardware store and buying a ready supplied tool box where half the tools are not really needed or an occasion where they would even be useful.