I've been in a situation where our alliance, having captured the outer outpost and having no contention or struggle from the competition, continued to push forward toward their spawn. We also realised we were behind with no chance to win, and people seem more interested in killing (we were bored waiting at the flag). This did indeed mean the other GC, was able to capture 4-5 of the flag points.

There is a downside to this activity (and not an imbalanced winning strategy), so I don't think it warrants a change. Players will just do what they want depending on how they feel in the situation. It is equally unsatisfying when the other GC just decides to not participate or put up a fight.