There has been huge progress in visuals, but the web is basically still a document and content delivery system decorated with a few animation features, not a full-fat creative multimedia OS.

And that could be because there are institutional forces keeping it at a certain level of clunkiness, which is far short of the requirements of professional media creators who work with video, 3D, and sound.

I suspect the real problem is that the walled-garden corporates don't want the web to compete with their lucrative app farming operations.

Unless that changes, the creative edges of the web will remained dumbed down.

And it probably won't change. Ever.

If that's correct, the original question has a simple answer: Web Audio is designed to meet the corporate requirements of Apple and Google, not the needs of web users or web developers.