If I follow, you are suggesting that web users protest a format that has been in the public domain for 17 years by instead using a format which has existed for less than 3, and in the process render content inaccessible to anyone not using a bleeding-edge browser?

Is there a good data set on energy requirements for transmission versus compression/decompression of data? Is it really that much in favor of compressed data?

As a concrete comparison, I downloaded the first webp figure on the page, "soft-drop-animation. The webp is 63,250 bytes.

I used imagemagick to convert this file into a gif, resulting in a 119,265 byte file. I then ran the result through gifsicle[0] with maximum compression (-O3) to losslessly optimize it, producing a gif that is 29,711 bytes; less than half of the size of the original webp.

As I noted higher on the comment chain, this usage scenario is particularly favorable to the gif format, while webp might come out ahead for photographic sources.

[0] https://www.lcdf.org/gifsicle/man.html