Yeah, in MW3 this happened to my team once. A guy got around 10 kills after he bottlenecked us into a spawn point on that one huge construction level, with the downed black hawk that you can shoot the turret from. The only reason we were able to stop it was that his gun took too long to reload. Soon his entire team tired to do it.
They need to fix the spawn points. Badly.
Heck, if there's an enemy near all the spawn points, why not just divide the numbers up? Say instead of having all 8 members spawn on X, have 2 spawn on A, 2 on B, 2 on C, and 2 on D? Etc, so that way at least one spawn point has a chance to fight back.