That’s what I might expect too, so I was surprised to find out that SPIR-V is usually substantially larger than text based shaders. It also doesn’t seem to compress optimally using standard algorithms. [1]
[1] https://aras-p.info/blog/2016/09/13/Shader-Compression-Some-...
Also if you anticipate the GPU being used as an accelerator, that is all the more reason to use a text based format because it allows for easy code generation.
If you think of AAA games, ML and whatnot, of course. But I doubt anybody will use WebGPU for those, to be honest.
The same with shadertoy, the storage or transmission of a shadertoy shader is never going to be significant compared to all the assets on the page.
The contention was that a binary representation is necessary to save space for storage or transmission. It just isn't.
However, binary form is way more compact for transmission, storage and performance. Almost nobody will use the text form except developers.