The main problem that I see is that people may do a lot of suffering from buffering. For instance in a function they write to a file. But they don't have an explicit close, so it doesn't get flushed until gc. Elsewhere you interact with the same file (perhaps you called the same function again) and get all confused when data that you know has been written, hasn't been. (And since you are sure that it has been written - a fact that you can verify by looking at it in an editor - you will look everywhere else for the problem instead...)