Because it doesn't block the thread. The idea is that this code is executed inside of a thread that, if it blocks, will cause the application to hang. For examp

Because it doesn't block the thread. The idea is that this code is executed inside of a thread that, if it blocks, will cause the application to hang. For example, in a GUI or a server. So, if its a thread driving a GUI, and it's blocked on user input, then the entire application interface will be unresponsive until it receives that input.