Plenty of makers in (probably) various countries finish bases with a matte grinding.
I have a Peter Layton paperweight, which has a matt base. I jokingly told Peter when I bought it, "People will think this is Chinese, because of the matt base!" so he laughed and signed and dated it for me (he doesn't usually sign paperweights.)
Chinese makers are now polishing the base of their recently made weights, so the 'matt base' rule can no no longer be reliably applied to Chinese weights anyway. It was used a rule of thumb in the past, but was by no means - as Kevin points out - exclusive to China.