The FGC was an outgrowth of an old PBEM game from back in 2001-2002. It (the PBEM) was set in 3062 initially, and each player took over only one faction for the game. There was a real disconnect between those of us playing in the Homeworlds and those people playing in the Inner Sphere, however. Everything was managed through orders sent to the GM or one of his subordinates, but the overhead was terrible. Players were required to submit once per week to the Email pool, which ultimately started to be abused by players leaving those players they were attacking out of the loop. However, the Clan players (don't know about the IS players) did use an old chat program to hold live Grand Council sessions. It was a bit of a hassle, yes, but from the perspective of RPing it was amazingly fun and engaging. The first game ground to a halt after several months due to player retention issues, but it was a fun few months nonetheless. Plus, I got to experience how butt-kickingly awesome the Hell's Horses could be to play around with. Hell, I think I still have the player's copy of those rules laying around here somewhere, but they're incomplete without the GM version I'm afraid.
The second attempt to run the game moved the year back to 3055 (ran the Jags that time around). This one barely made it a month, as the GM had RL issues and rules problems manifest themselves in force. The complexity of his rules were such that it wasn't possible for him to bring in any other help, and the game ended. Shortly thereafter, a few of us on the boards decided to start up a purely RP game based a bit on the failed PBEM. The idea caught fire, the forum exploded, and a phenomenon was born. Over time, the game evolved to add the different elements the PBEM had tried to contain, but the overlarge scope & shifting player base are what, in my opinion, finally broke the beast's back.
I personally worry about making the scope so large as to include all the Successor States and Clans, based on my past experiences. Am I saying it would be impossible to do? No, just that I worry about the effects of overreaching on what we want the game to be. That's my reasoning for stressing simplicity.