You made me google "no-halftone-screen". I'm lost!
when you used analogue b/w reproduction to produce a 'zine, continuous-tone images would be badly posterised unless you used screens to halftone them
It's a paper printing semi-analogue process to solve the problem (not enough colors, need to simulate colors spatially) that that semi-digital electronic screens use dithering for.
It's dual to "anti-aliasing", where we use an abundance of colors to simulate missing spatial resolution.