It wasn't an oversight/mistake rather an intentional choice for WebGL to support mobile devices with OpenGL ES 2.0 (and later 3.0) which doesn't support compute shaders amongst many other things. Since it was the baseline exposure of GPU capability they wanted it to work universally not just on desktops which were on the way to being the minority of web users. We GPU is getting it because WebGL is already there as a baseline plus it has been nearly a decade and mobile GPUs are more capable.
I know, the problem was never moving past ES 3.0, and now we have to wait yet another 10 years for widespread deployment of WebGPU MVP 1.0, given past history.
So that, alongside the usual blacklisting issues, makes native the only option for anyone that wants to exploit the full potential of the underlying hardware.
