So the most important question is: why isn't this interface implemented in any browser yet?
That a BufferSourceNode cannot be abused to generate precision oscillators isn't very enlightening.
Partially because in addition to the interface itself it relies on a bunch of generic worklet machinery which also doesn't exist in any browser and is not trivial to implement in non-sucky ways.
But also partially because the spec has kept mutating, so no one wants to spend time implementing until there's some indication that maybe that will stop.
I think there were some false starts where previous specs were written and then found to have issues.
So basically, Web Audio is unusable in release Chrome on a measurable subset of user machines, for multiple releases (until the fix makes it out), all because of AudioWorklet. Which isn't available yet.
I am being a little unfair here, because this bug isn't really the fault of any of the people doing the AudioWorklet work. But it sucks, and the blame for this horrible situation lies largely with the people who designed WebAudio initially. :(
Just skimming it a bit, it seems like they tried to make the same kind of "managed" framework for an audio graph that SVG spec does for vector graphics. And even if SVGs are janky the static image still succeeds in serving a purpose. But if you get dropouts or high latency in audio, there isn't much more it can be used for. (Aside from browser fingerprinting :)