Brass is one of the easiest metals to turn. It requires no lubrication and no fiddly about with top rakes to grind and hone. So a piece of square hss tool only needs a lick on a bit of flat glass or plate and a bit of Brasso or an oil stone.
Classically, brass was turned with a diamond shaped graver on a hand rest which-if you think about it, was a tangential tool.
I learned with a bit of broken window glass on wood. Not everyone's thing but we had no choice.
Norman