I agree on the defending thing...
but there are some exceptions.
Sometimes people are obviously 'raping' from a fixed position, without any tactical advantage to the side of the 'camper/raper'. I think I can argue several cases every day of people that 'rape/camp' purely for a point advantage. Nothing else...
In general I see this as unsportsmanlike behavior, more looking for 'getting the highest score on the list' and/or 'frustrating other players'.
I find these kind of people annoying, both playing with them and against them. They contribute very little ; at best they manage to clear a spawnpoint or eliminate some enemy tanks. There are some situations where raping a flag is usefull, for example if there are only two left - half the team dies attempting to spawn, the other half too weak to defend the remaining flag.
Anyways. Long story short ; I think we all know a few players that we have this gut-feeling with ; I do rape sometimes, and I certainly enjoy getting high scores. But it's secondary to teamplay, to the team goal. Efforts should be directed to achieving things that are beneficial for the group, not just yourself. Well, in an ideal world anyways