Meanwhile, for web, most web games are... uhhh, web games? Mobile-like? So, you usually aim for the best performance where every shader ALU, drawcall, vertex and driver overhead counts.
That said, I agree on your take. Things such as this (https://voxelchain.app/previewer/RayTracing.html) probably would run way worse in WebGL. So, I guess it's just a matter of what happens in the future and WebGPU is getting ready for that! I hope that in 10 years I can have at least PBR on mobiles without them burning.