The core joins involve monsters up to 25,000, and this change hardly affects diplomacy at all.
In your opinion, if the diplomacy limit is reduced to 10,000 (7 ducks), will diplomacy still be overpowered?
Added after 1 hour 16 minutes
There may have been a misunderstanding due to the wording of the diplomacy condition.
It refers to the total AI value of the joined stack.
That is, 25,000 is, for example, 18 ducks = 25,000/1350.
This is the maximum stack of ducks that can be joined in a game with Fresh Mod 3.0.
More examples of maximum joinable stacks:
4 angels = 25,000/5019
8 royal nagas = 25,000/2840
12 cavalry = 25,000/1946
16 manticores = 25,000/1547
20 pitlords = 25,000/1224and so on.
If the stack is even one unit larger, it will either fight or flee, depending on the strength of your army.