Input and Parameters (Material Functions)

Hey guys, I just started the deep dive into the UE4 material editor and I’m following a tutorial from artstation learning (Creating Materials in Unreal Engine - with Kem Yaralioglu). On the 3rd part of the course, he starts to create a master material (using a material function) for future projects and I was kinda confused by the use of inputs and parameters in the function. On the tutorial, he uses a bunch of input nodes to set up the variables for the master material and, on another material function, he references the first material function (the one with all the nodes) and create parameters for all the inputs. My question is, what is the reason for the input nodes? Cant I just create the parameters on the first material function instead of using the input nodes and then creating parameters on another function? Seems like the use of these input nodes are kinda pointless. I’ll attach some images from the editor to help illustrate my point.

Any help would be greatly appreciated, thanks for your time!