Because it is clearly messing with more than just “lighting”. While the spatial models appear untouched, it heavily changes textures, inventing details that simply were not there before, no matter what lighting. And then some of that “lighting” is also used to imply spacial details that were not there before.

All of that creates that incredibly artificial and sloppy overall impression at “100%”. At lower percentages it likeky won’t be better, the sloppiness will be merely more diluted and therefore more tolerable.