> "But instead this was just another development thread Google single-handedly stopped out of nothing but ego?"

There's a reasonable cost/benefit argument against standardizing JPEG XL in browsers. You don't have to agree with it, but JPEG XL proponents shouldn't just ignore it.

The argument is: (1) the cost is large -- implementation and maintenance of a complex image codec takes time, and image codecs are high-risk from a security perspective. (2) the benefit is relatively small -- it needs to provide a clear advantage over existing alternatives like jpg, png, webp, avif in some significant general use cases.

Now, you don't have to agree with that argument -- e.g. you can argue the cost isn't that high, or that there are valuable advantages to jxl for significant use cases that aren't covered by existing alternative.

But you do need to engage that argument.

Otherwise what else do you have? Popular demand isn't going to work, because you're in a chicken-and-egg situation. I suppose you can try to bribe and/or bully key decision makers for all the major browsers, though I hope that wouldn't work.