Don't you arbitrarily (and for no reason the AI can see) build up and attack the AI? For reasons?
Your thought processes might have been entirely different (they're near *your* luxuries early on, they're near *your* expansion corridor early on, that's a nice continent you have/had there, etc), but you're certainly more chaotic than the AI in your diplomacy choices. Mostly, anyway.
Think of MP games, if there was no messaging system, but pretend they were AI players. A lot of shit doesn't make sense from your perspective, and you were being really nice to them....
I'm not giving the AI an excuse to be poorly programmed, but at least Civ 6 has some reasons for the behaviours. If you were them, you'd think how badly programmed the Human.Intelligence was, because shit happens to them all the time, for seemingly no reason at all. Even when they've got a huge fucking navy. And you were the Vikings.
So suck it up. They're trying to win too.
Seemingly random AI diplomacy often isn't, but I can understand the complaints of them not attacking you *properly* for *stuff*, chaotically and seemingly without reason. Shit combat AI and shit diplomacy AI aren't necessarily the same thing, though one leads to the other. Still, I'd rather good combat AI, regardless of seemingly "human" decisions from the diplomatic side of things. A big stick can be scary, spoken however you please.