"Material From selection group"
What it is supposed to do for you is ... if your Material has been "emptied' maybe by AutoUV process of you applied some other material ... you can make it so that material is "reapplied" to faces in selection group with same name. It is as if "selection group" is a "back-up" for Materials.
"From Selection group" process does not make a new material for you.
"the three options below are necessary?"
Yes ... they are needed.
I have vast numbers of selection groups and materials and I like to shuffle them back and forth depending on my mood. So being able to match by partial is needed. Entering a complete name would not be so useful to me. But you can do it.
What it is supposed to do for you is ... if your Material has been "emptied' maybe by AutoUV process of you applied some other material ... you can make it so that material is "reapplied" to faces in selection group with same name. It is as if "selection group" is a "back-up" for Materials.
"From Selection group" process does not make a new material for you.
"the three options below are necessary?"
Yes ... they are needed.
I have vast numbers of selection groups and materials and I like to shuffle them back and forth depending on my mood. So being able to match by partial is needed. Entering a complete name would not be so useful to me. But you can do it.