>avif is just better for typical web image quality,

What does "typical web image quality" even mean? I see lots of benchmarks with very low BPPs, like 0.5 or even lower, and that's where video-based image codecs shine.

However, I just visited CNN.com and these are the BPPs of the first 10 images my browser loaded: 1.40, 2.29, 1.88, 18.03 (PNG "CNN headlines" logo), 1.19, 2.01, 2.21, 2.32, 1.14, 2.45.

I believe people are underestimating the BPP values that are actually used on the web. I'm not saying that low-BPP images don't exist, but clearly it isn't hard to find examples of higher-quality images in the wild.