Comment by VanTheBrand

JPEGXL literally is able to display images and colors that jpeg and png cannot (32-but floating point, layers, emission independent transparency, spot colors, built im depth maps). It’s not just about compression optimization. So for those use cases standard JPEG and PNG alone will never work. There are “updated” versions of JPEG that support some of these like HDR but those won’t work with any old browser either so back to the same issue.