I really don’t know why you would be surprised, but you said you were. Good and bad are hugely explanatory that anybody from a scientist to a child can understand and use them and convey great meaning. Here’s a larger quote from that article of Rothbards:
"The concept of “good” (and therefore of “bad”) is only relevant to living entities. Since stones or molecules have no goals or purposes, any idea of what might be “good” for a molecule or stone would properly be considered bizarre. But what might be “good” for an elm tree or a dog makes a great deal of sense: specifically, “the good” is whatever conduces to the life and the flourishing of the living entity. The “bad” is whatever injures such an entity’s life or prosperity. Thus, it is possible to develop an “elm tree ethics” by discovering the best conditions: soil, sunshine, climate, etc., for the growth and sustenance of elm trees; and by trying to avoid conditions deemed “bad” for elm trees: elm blight, excessive drought, etc. A similar set of ethical properties can be worked out for various breeds of animals.
Thus, natural law sees ethics as living-entity- (or species-) relative. What is good for cabbages will differ from what is good for rabbits, which in turn will differ from what is good or bad for man. The ethic for each species will differ according to their respective natures.
Man is the only species which can — and indeed must — carve out an ethic for himself. Plants lack consciousness, and therefore cannot choose or act."
They are self-evident and natural, meaning, they are “of” a person, not prescribed for them, but “of” each individual naturally. If there is any prescribing it is simply justice providing equality for each person to pursue their just end.
Yes various benefits, near infinite, are potential when each person is given the potential to actualize without injust interference.