Alright, but in practice a unit that can get from one continent to another through hostile waters filled with U-boats would benefit from embarked defense and sight. I know I'm oversimplifying their role in the Italian Campaign but Italy has a lot of coastline to deploy amphibious units and I'd expect any Brazilian force fighting abroad to be heavily tied to their navy. On the other hand the Marine is completely isolated from upgrade paths, which makes it a bad target for UU replacements.