I've got three keyboards connected to my PC and I could get a fourth one from another computer if I would ever need it... that's really not that much of a problem. And even if you wouldn't have this multi-key-press-limitation-thingy, four hands on one keyboard is already very... unpractical.

Also, I'd like to make clear that I agree that not many players use splitscreen, but it will be impossible to have a perfect timing, if you depend on 4 individual players all playing on different computers.

As recording a 4-way splitscreen (or even a normal 2-player splitscreen) wouldn't make an interesting video with resolutions being limited to what people considered 'small' back in 2000 already, we'd already need the LAN for someone else to record the things. Imagine this: the splitscreened computer is the stage and the screen recorder is watching the play from the other computer over an LAN-connection.

Now, if we'd have to split up our stage over two computers, timing will suffer. Even if you are still able to press a certain button at both computers at the same time, it would never get as perfect as it would be if everything were done on the same computer due to network slownesses.

So that's why I asked it.