Re from Ostermiller: "I'm not sure exactly what Google's motivation is, but they are pushing these new image formats hard. By creating the impression that the new formats could help SEO, they are getting websites to use them before there is browser support in an effort to pressure other browsers into having to support them."
I'm not sure either why this is happening. But I've continually read that the text in an image file is searchable and used for search. It's also obviously helpful to reading code on a page that might have many images. If I'm looking for one of a blue dog collar, then the file name that had that text would be simpler.
But with webp file names, all those benefits may be history, as files all read like MTk2MzAyMjAxODE4MTk1NDgz. My impression is that Google image search is becoming useless for most users. I personally have run, not walked, away from many of the major sitebuilders like Shopify and many others that will now not produce a human-readadable .jpg in the code. In fact, if I upload a clearly-described jpg image, I can only save that same image from the displayed page in the webp format.
So I have no idea if that image would ever be searchable without an alt tag. But I know that many, if not most everyday website designers will often skip over alt tagging. Many Shopifiers don't know what it is. However, Squarespace and Wix will not accept a webp image to upload. Nor will common graphics programs like Photoshop Elements 2020. And the world's largest art site, Fine Art America, doesn't recognize that format either. Craigslist, for one, will allow a webp image to be uploaded, but then automatically converts it to a readable .jpg. Maybe they assume the webp format will not be seen in searches.
Joe R.
Addendum update: I've been asking tech support at a number of major website builders about this. They seem practically unaware or unconcerned about the issue. Or a few that understand why I'm curious about why anyone would want to see their simple, descriptive jpg get magically transformed into a webp, like this one:
9eda45a3ef19ab7f33b3448ff78f85aa_b5a7caa6-a1fb-46a4-b75e-3515dc7a7b4e_360x.
The best informed techs all said to download an app or run some program from another website to convert it back. Some said to just use Photoshop and resave it. All that so my image, which took an average of 1/100th of a second to be seen, can now more speedily be seen at 1/200th of a second.