Comment by whizzter
No, it's a valid complaint. Even before hardware raytracing a huge amount of code was moving to compute shaders, most global illumination techniques in the last 10-15 years is easier to implement if you can write into random indices (often you can refactor to collecting reads but it's quite cumbersome and will almost certainly cost in performance).
Even WebGL 2 is only equivalent of GLES 3.1 (and that's maybe a low 4.1 desktop GL equivalent). I think my "software" raytracing for desktop GL was only feasible with GL 4.3 or GL 4.4 if i remember correctly (And even those are kinda ancient).
WebGL2 is GLES 3.0, not 3.1 (that would be big because 3.1 has storage buffers and compute shaders).