I know it, everyone knows it; AI diplomacy is suicidally bad.

"Here's some money to help raise troops against our mutual enemy, the one besieging one of your towns right now. Take it as a gift of the friendship between our nations)"

"We have nothing to give you in return, so we must refuse."

"But, I said it was a gift."

"It is pointless talking to you now."

I use money to try to maintain the flagging sides of conflicts on my borders. Better two moderately weak nations fighting one another than one great power fighting me.