You can do that without async in python. What did you find specific to it?

I imagine he means without having to understand/use the platform or framework equivalent of select/poll or start dedicated threads or write a threadpool to handle reading from streams simultaneously without blocking. Now he has someone else wrote that code for him ;)

It's live and immediate and simultaneous, which you can only get with async or multithreading.

Async Python gives you the ability to set up functions that act upon multiple stdout/stderr streams and process them in real time.