Of course there are tons of better formats than JPEG but it needs to be understood that the most important feature of JPEG is to be exchangeable. It doesn't matter what your shiny new web browser supports, JPEG is considered supported everywhere and all editorials actually refuse to accept anything other than JPEG. You can't just break everyone's workflow because Google decided to force WebP (for purely selfish reasons, of course). The web browser is actually one of the least important platforms for JPEG. To day JPEG still executes its mission perfectly and with huge bandwidth increases it doesn't even matter how large the file is.
This article* makes the case for mozjpeg cleanly beating webp when we are above 500x500px image sizes. So. There's a lot more performance/compression to be gained within the jpeg container format than people generally argue for.
The same thing sort of happened in the compression realm. ZIP is the pretty much the defacto winner for that type of file movement. Oh people use others in a lot of cases. But even when pkzip 2.04 came out there were better ones. Yet here we are still 30 years on using zip. Heck the zip alg is even used in many picture formats.
It helps that in most cases when people make a zip the compression is a secondary feature. What people want 90% of the time is a container format to put multiple files or a whole folder structure into one file. .zip or .tar.gz do this just fine, even if their compression factor and speed aren't that great by modern standards.
Same with jpeg: Most people want to just encode images, reducing file size by 10% is a negligible win for most people
