Create Blendshape

While i saw this unique tutorial on how to make hair systems and the settings for it..i discovered something interesting about the idea of "create blendshape." as i sat there watching it..the use of that same node that we all use for just geometry it can be use for curve,joints and etc. as just and output/input history. like what u use a color blend for..its the same thing but can link that output/input into other things.