There are very few people working with image codecs, and you will not find a codec "virgin" among people responsible for these subsystems.
One of the main JPEG XL contributors is a WebP contributor and a Google employee. If JPEG XL got shipped first you could make the opposite conspiracy from that!
No, not really. If JPEG XL had a time machine and made itself deployed on the Web before WebP, I'm pretty sure nobody would want WebP in. It'd be an objectively stupid idea to adopt WebP having JXL available, and I'm pretty sure even WebP authors would agree with that.
The Web is not supposed to be a Katamari Damacy of codecs. It doesn't need multiple redundant or worse ways to do the same thing. There's a high cost of adopting a new format Web-wide, so it's rational to do it rarely and only when benefits outweigh the costs.
Thats a totally different scenario though. AVIF and JPEG XL both have gaps, contemporary adoption makes sense. Its like trying to argue "we dont need PNG, we have jpeg"
One of the main JPEG XL contributors is a WebP contributor and a Google employee. If JPEG XL got shipped first you could make the opposite conspiracy from that!