If I tell someone, "bring me a sandwich or a bowl of chili," and the person brings me a bowl of chili, that person has done exactly what I told them to do.
What if they get bored waiting at the counter in the cafe and come back empty-handed? 'Cos that's what can happen as soon as IO is allowed into the picture; particularly so with network IO.
The problem is that combining this with multithreading makes for a combinatorial explosion of possible states that you might have to deal with. It's just not feasible to exhaustively specify everything., and leaving things implicit means that you're expecting the computer to do things you haven't told it to do.
Sure, there is complexity. It's easy to make assumptions or forget real-world details too. But you DID tell it to time-out, because that's how the I/O library is specified.
