Diplomats - What's the Point?

[pezhetairoi]

A typical diplomatic effort:
Us: Look, this war is dragging on and on. You can't really win, so why don't you agree to a ceasefire?
Them: Ceasefire? Never! We will destroy you all!
...
Us: We've burned down your capital. Why not agree to a ceasefire, since you seem to be losing the war?
Them: Ceasefire? Never! We will destroy you all!
...
Us: Okay, we're about to attack your last city. How about agreeing to a ceasefire now? Your city isn't worth much to us...
Them: Ceasefire? Never! We will destroy you all!
...
Us: Okay, we've sacked all your cities and burned down your palace. We're about to cut your head off. Ready to be reasonable?
Them: Never! I will destroy you all!

Once you've got all your trade rights, is there any point in having diplomats?

https://www.youtube.com/watch?v=2eMkth8FWno

ARTHUR:
You fight with the strength of many men, Sir Knight.
I am Arthur, King of the Britons.
I seek the finest and the bravest knights in the land to join me in my court at Camelot.
You have proved yourself worthy. Will you join me?
[silence]
You make me sad. So be it. Come, Patsy.

BLACK KNIGHT:
None shall pass.

ARTHUR:
What?

BLACK KNIGHT:
None shall pass.

ARTHUR:
I have no quarrel with you, good Sir Knight, but I must cross this bridge.

BLACK KNIGHT:
Then you shall die.

ARTHUR:
I command you, as King of the Britons, to stand aside!

BLACK KNIGHT:
I move for no man.

ARTHUR:
So be it!

ARTHUR and BLACK KNIGHT fighting:
Aaah!, hiyaah!, etc.
[ARTHUR chops the BLACK KNIGHT's left arm off]

ARTHUR:
Now stand aside, worthy adversary.

BLACK KNIGHT:
'Tis but a scratch.

ARTHUR:
A scratch? Your arm's off!

BLACK KNIGHT:
No, it isn't.

ARTHUR:
Well, what's that, then?

BLACK KNIGHT:
I've had worse.

ARTHUR:
You liar!

BLACK KNIGHT:
Come on, you pansy!
Huyah!
Hiyaah!
Aaaaaaaah!
[ARTHUR chops the BLACK KNIGHT's right arm off]

ARTHUR:
Victory is mine!
[kneeling]
We thank Thee Lord, that in Thy mer--

BLACK KNIGHT kicking ARTHUR:
Hah!
Come on, then.

ARTHUR:
What?

BLACK KNIGHT:
Have at you!
[kick]

ARTHUR:
Eh. You are indeed brave, Sir Knight, but the fight is mine.

BLACK KNIGHT:
Oh, had enough, eh?

ARTHUR:
Look, you stupid bastard. You've got no arms left.

BLACK KNIGHT:
Yes, I have.

ARTHUR:
Look!

BLACK KNIGHT:
'Tis but a flesh wound.
[kick]

ARTHUR:
Look, stop that.

BLACK KNIGHT:
Chicken!
[kick]
Chickennn!

ARTHUR:
Look, I'll have your leg.
[is kicked]
Right!
[whop]
[ARTHUR chops the BLACK KNIGHT's right leg off]

BLACK KNIGHT:
Right. I'll do you for that!

ARTHUR:
You'll what?

BLACK KNIGHT:
Come here!

ARTHUR:
What are you going to do, bleed on me?

BLACK KNIGHT:
I'm invincible!

ARTHUR:
You're a looney.

BLACK KNIGHT:
The Black Knight always triumphs! Have at you! Come on, then.
[whop]
[ARTHUR chops the BLACK KNIGHT's last leg off]

ARTHUR:
Oh? All right, we'll call it a draw.
Come, Patsy.

BLACK KNIGHT:
Oh. Oh, I see. Running away, eh? You yellow bastards! Come back here and take what's coming to you. I'll bite your legs off!