It's not just the diplomacy that makes the current game basically default to endless war (the diplomacy aspect was also touched on in this post - https://forum.game-labs.net/topic/40442-about-international-stress-and-tension/)
I've also realized that - because your budget -immediately- doubles (more or less) when you go to war - and also doubles your research budget - you are ALWAYS going to be advantaged to be in a basically limited war with some other power, if only so that you are getting more research more quickly.
If you are able to stay in a war with a power you've already beaten down, and you don't let them surrender for peace, and you kill their ships as soon as they leave port, one-by-one..... it's the best possible scenario for you to increase tech and advance past any power who's not also at war. And the same in reverse - if the AI nations are at war, they are advancing and you're not...