Horseradish so you would have spent 20 min just building stuff and then never get to use them. Thats a waste of time imo.
Since they stayed they could very well have had an experimental walking up on your commander anytime, turning the gamefield totaly around. Im quite sure that if all your enemies just left as the battle was going to start becouse they had 5k less score you would have been a bit pissed as well.
If it is one persons desire to ruin online play for all so be it
But you can be freaking sure the host wont allow him into his games anymore unless he got atleast a semi-good reason for leaving.
Imagine CS shoutcasts final where the other team suddenly gets a leaver becouse the scores are 2-5, totally ruining the game for the rest of both his team and his oponents, not to mention the people watching.
Thing is that if we dont get anyway to handle leaving in the game such as % of games completed shown in stats et.c there will instead be a big community keeping third party banlist programs, Then you wont be able to join any game at all after a while HorseRadish.