Symbol.disposeAsync - what is the use case?

I have questions
1

I tried to follow the reason await using thing = await that() is anyhow desirable when using thing = await that() would work practically the same ... can anyone please enlighten me around this topic?

const disposable = value => ({
  value,
  [Symbol.dispose]() {
    console.log('disposed');
  },
  async [Symbol.disposeAsync]() {
    await Promise.resolve();
    console.log('disposed');
  }
});

const testSync = () => {
  using ref = disposable('sync');
  console.log(ref.value);
};

const testAsync = async () => {
  await using ref = disposable('async');
  console.log(ref.value);
};

Why or when await using does a better job than a Symbol.dispose that returns an async function anyway?

const disposable = value => ({
  value,
  async [Symbol.dispose]() {
    await Promise.resolve();
    console.log('disposed');
  }
});

Where is the observable need for wait in using that makes any difference in there, when I believe a synchronous dispose that returns a promise (async function) would still run to completion once invoked?

Thanks in advance to anyone willing to explain the need for await using as I really struggle to see why, what, or where that is better than just using.

2

somebody mentioned that is for cases where you want to block asynchronously before the rest of the code executes ... OK, I get it now, but I still wonder what are the use cases for that that made Symbol.disposeAsync part of the specs ... looks like a performance hazard and an easy shenanigan to avoid when async [Symbol.dispose]() {} is available and working ... does anyone in here have a use case for a desirable blocking async dispose? :thinking:

Thanks!

3

OK, I got examples (elsewhere) and read the whole conversation around this ... I think we can close this question of mine as it's clear everyone has a say, all I wanted to understand s a why ... but that's covered at this point. Apologies for the noise, I still think await using was a very ugly decision, I believe also nothing I can do about it at this stage of affairs.