alt Hacker NewsThere are some other advantages, such as jxl being able to progressively load in web broswers, while avif can't for some reason. However avif compression seems to be better at low qualities, which might be relevant for some web applications, if one doesn't want to serve both jxl and avif.
There's a good visual comparison here:
JPEG has had progressive loading on browsers since the almost the very beginning. But everybody stopped using it because it added slightly to the file size and "looked ugly." According to most web designers, anyway, who would actually rather serve the user a blank page than have even one of their precious pixels out of place.
I haven't actually seen a progressive jpeg rendering since the dialup days at any rate.