A good example is say you want to handle 100k TCP sessions concurrently. You probably don't want to launch 100k threads considering the overhead in doing so and constantly switching between them. You also don't want to do things synchronously as you'll constantly be waiting on pauses instead of doing work on the 100k sessions. So you launch 100k instances of it as an async function and they all stay in a single thread (or couple of threads if you want to utilize multiple cores for the work) and instead of constantly waiting on pauses it simply works on the log of queued up events.
Same code flow just it allows you to launch the same thing multiple times without having to wait for the whole thing to finish sequentially or wait on the OS to handle your threads.
Same code flow just it allows you to launch the same thing multiple times without having to wait for the whole thing to finish sequentially or wait on the OS to handle your threads.