[solardev]

Because it's Google. Apple in particular didn't want to play nice for many years and tried to pitch HEIC support instead (or AVIF these days). WebP came out in 2010, right when the whole mobile app vs web app thing was heating up and Apple/Google were fighting for mindshare. It wasn't until 2020 that Apple added stable support for WebP.

Neither offered a big enough improvement for end-users to care.* Cloud operators did care, and Imgix and Cloudinary can automatically transform older formats to WebP or AVIF, for example: https://docs.imgix.com/en-US/getting-started/tutorials/perfo... and https://cloudinary.com/documentation/image_optimization#auto...

There are also a bunch of Wordpress extensions that can do the same, and FOSS proxies too.

* Hell, you think PNGs are bad? We still use animated GIFs and MP3s, even though both are terrible by today's efficiency standards. Sometimes good enough is good enough.