Usually when people criticize UNIX i/o behavior for not being proper what they want is for it to do that thing NT does where processes freeze indefinitely at the first sign of trouble, and you have to pull out the task manager and kill the thing. Nice thing about UNIX is pretty much the only time things get that bad is when you implement sigchld wrong, and the times when we want that behavior, like with linger, we can specify the number of milliseconds it should hang. In fact, NT is so zealous about the process freezing thing that even when it comes to the signals it's required to be able to deliver by the ANSI C standard it will spawn a thread in your program just to do it. Being able to drop connections yolo style without the kernel having strong opinions is pretty important if, for example, your app is getting attacked by a slowloris and you need to shed resources while responding to requests from the main process. That's why proper operating systems are rarely production worthy.