That was part of it, the other part was the amount of variables for each ship that needed to be passed through the lines, even telephone line for the time.
For example , with two ships, we are talking location, shield strength, emp, drones, weapons, etc. etc all at a constant update. with 6 that is a lot of info. Mind you, the amount of info that SFC passes along, is a lot more than say WoW, or the average FPS.
I believe Either Scott or Dave explained it like that in the long ago. Just way too much info to share with larger groups. I mean, imagine if all 6 players had 3 ships each, all drone carriers. That's a lot of information to pass along at a constant rate. Anyways, It's a good question, and I'm glad you brought it up.
Stephen