Wouldn't "super fast game rendering" be done by the GPU via WebGL?

For 2D games it's much more convenient to pixel push directly than to deal with vertex buffers, index buffers, shaders... Unfortunately graphics cards are not optimized for that scenario.

Convenient, but "super fast"?

And though it's a matter of opinion, I disagree. The GPU is easier for me to use for things like screen-space shading, alpha blending, sprite transformations and distortions, and it all performs much faster than the equivalent CPU render code.

A lot of game logic also runs on the CPU

canvas bitmaps are only useful for rendering though.

Assuming that also implies access to typed arrays in general, then applications that involve number crunching become a lot more feasible in JS too.

Huh? We've had typed arrays in JS for years. I think they originally went in to support WebGL, but you can use them for other stuff too.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

Direct access to typed arrays from WASM without having to copy them over whole first, or use the memory buffer of the WASM module. You can't really write a "true" generic in-place sort in WASM right now, so to speak, because there is always a copying back and forth step.