It depends on your goal for your goats.
Breeding or lactating females do need the protein. Kids will need it.
If you are concerned about minerals, get purina wind and rain storm. In the cattle section.
This is NOT a dumb question. So many different kinds of products are lumped under "Mineral Block" and you have to ask what is meant.
I had to wean several doelings before I was completely happy to. I bought this to help keep up their protein, growth, and health. I am not using it currently. I think it is something that is useful in some circumstances, but is not universally helpful.