No one is saying you have to be nice and avoid PKing and looting people. The point is that if you make a habit of multi-killing and full sac'ing people, you'll get one of two outcomes:

1. They'll stop fighting you or maybe even stop logging in when you're around unless they have friends to help them out.
or
2. They'll delete.

I don't see how either of those options makes CF more fun for anyone but maybe you(?). There is a wide gray area between the extremes you've set up in your mind in which CF can remain competitive and vibrant for all involved.