Why Does the sleep() Function in JavaScript Use a Promise?

sleep() is defined as:

const sleep = (ms) => new Promise((r) => setTimeout(r, ms));

Why can't we just use setTimeout() without a promise involved?

Using a Promise allows us to await the timer, which we can't do with just setTimeout(). This allows us to write our code that looks more linear like:

// before
await sleep(time);
// after
await sleep(time);
// more

Instead of

// before
sleep(time, () => {
  // after
  sleep(time, () => {
    // more
  });
});