At first I was going to mock this statement, but now i'm seriously curios about your experiences.
When I think of pure unadulterated PvP. Here is what comes to my mind.
Eve Online - I jump you, web you, scram you, prison shank you, take away the equivalent of a week of your life, mock you in chat, bump your pod, ransom you for money, then kill you after receiving payment for the lulz. I join your corp scam the entire hangar rob your blind, then give away some of your assets in Jita, like a rapper making rain because why not. Run scams telling new player that if they transfer their assets to me I will let them join our super cool alliance, only to keep them and laugh, then post about on the forums, that's a game in and of itself.
League of Legends - I autolock a role based character without looking at my teams composition, I rage at a newer player for feeding, talk ■■■■ to them about how on earth they made it to X level of play, I stand outside bushes, cue taunt and play music in my live stream to show disrespect, work on timing the best way to kill you to make sure it is funny, and disrespectful.
Minecraft - Factions PvP. I TnT cannon my way into your base. Kill you and your factions mates repeated until we can claim your land, and take all your stuff. After pillaging the base, writing insulting words in nether block and lighting it on fire, just to ass salt to the wound. Or I break into your base in the middle of the night using cobble cancer methods plus TnT, and or Creeprs. Rob your entire Faction while you sleep. Perhaps, a faction full of 12 year olds all asleep on Christmas morning... Better yet, roam around spawn looking for new arrivals, jump them while there setting up a basic shack and farming, gathering all they have managed to amass and throwing in into a pile of lava.
Now, tell me about some of your experience where. "permanent PvP often even encourages good manners between players" occurred.