I do it. I have got 3 computers permanently networked and can bring in the fourth at times too. I can even have multiple sequencers running and sync them all too but I am not a great believer in that. Then you have to save say 2 or 3 different sessions in order for the music to all playback. I am running my main DAW (Studio One) as the total sequencer but instead it can talk to the other computers which are mainly in virtual instrument mode.
These parts can be rendered into audio as well once they are locked in removing the need then to even boot up the other machines as you head toward the mixdown.
Another use is for say running 2 or 3 very nice sounding reverbs. I can do that too but I even print those stems as well.
I have network, midi and audio digital and analog, stereo and multiple outputs between every machine in both directions. Sending audio over the network works fine too.
Having a system over multiple computers is luxury I guess but it is amazing though. Even with the most massive of sessions each machine is only taxing 20-30% of its resources. The total is greater than the sum of the individual parts. You do have to watch connecting multiple digital signals together etc. You need to think about what will be the master digital sample clock and which others will slave etc. But it is easy to sort out.