Inconsiderate!

[Greatguardian]

It's just a math problem. If the spot is good enough such that farming there with competition is better than farming elsewhere without competition, then it's worth it to fight for a spot. This is especially true when the relative skill of the groups is tilted in the favor of the "invader".

Invading a camp where you would be worse off than if you had just taken an empty camp elsewhere is just stupid, though.

Do I consider it rude? Not really. No one has any sort of singular claim to any zone or monsters. It's rarely personal. People will simply act in the best interests of their group.