But there is a loss in quality! The dithering is noticeably worse. Notice the light outline on that red-ish thing in the top middle of the image. I bet I could've gotten the 10kb decrease by just lowering the JPG quality.
Umm...how can you claim a loss in quality without looking at the original? The linked page shows two lossily compressed versions of an unknown original image. You're commenting on which image subjectively LOOKS better to you, not on compression quality.
Take a look at those red and orange "things" in the center of the image in the PNG/WebP version. My bet is on a loss in quality.
My point was just that they're showing a lower quality image that is is lower in size. Great, ice is cold.