curl-6 on 05 January 2018
It's just an easy performance win.
As a game with open non-linear worlds running at 60fps, Odyssey has to make cutbacks to look as pretty as it does, and the devs just decided that using dithered transparencies was a less jarring tradeoff than, say, lowering the screen resolution.
It's not like this technique hasn't been seen on the Saturn; plenty of Wii U, PS3, and 360 games used dithering as a shortcut. Take a closer look at the foliage in Battlefield Bad Company 2, to use an example off the top of my head:
