> On the technical side, webp support still isn't like png.

Oh that's a good point.

I see lossless WEBP mostly as a way to save bandwith where PNG would have been used. If you've got a pipeline where, anyway, you already "crush" your PNG file, you may as well also generate a lossless WEBP file and serve that: all browsers support it. And you can fall back on the optimized PNG should the browser not support WEBP.

I mean: I use WEBP, but only lossless WEBP, as a replacement for PNG when I'd serve PNG files to browsers.

But for that one usecase: showing a PNG file in a webpage, I don't see that many downsides to lossless WEBP. It saves bandwith.