Consider a 3 vs 3 game of infiltration, alpha has 60 points, bravo is on 80, point limit of 90. The game is nearly over and alpha have secured the flag, there is no hope for bravo now. Out of desperation, an asshat on bravo joins alpha, the teams are now 2 vs 4, alpha caps and should win the game, but because of the asshat from bravo, they only get 25 points. The game ends 83 - 60 to bravo. Everyone on alpha is pissed but they cant do anything because all the bravo's F11 the ensuing vote kick, as they always do.
The point system can be exploited, and it happens. Maybe not in gathers etc, but it should still be fixed so that retards in public servers cant do it.
Automatic team balance scripts have partial effect, but don't get rid of the problem completely.