Photo etching is used for all kinds of things including making plates for printing, I'd guess that's the more direct ancestor.

Direct ancestor probably is mask-and-tape PCB design process, where the optical step also serve to shrink the (hand made) mask to significantly smaller size of the final board. In fact silicon masks were for a long time designed using essentially same process.

In fact if you want to make something mostly flat with small features some variation of photo etching process tends to be the easiest and most repeatable way to go about that.