Cities you get from peace deals don't add to warmonger penalty, and liberation erases a portion of warmonger penalty. Naturally, you don't get warmonger penalty with your friends unless you go completely nuts, and if you have partners in that war, warmonger turns into a common foe bonus. There are ways around warmonger penalty. The tech penalty is more a nerf to the AI, which loves to settle in that never grows past 4 pop, to prevent them from becoming unstoppable runaways (tech penalty also applies to puppets). Wide empires that got there legitimately and take the time to grow (i.e. 99% of player empires) still have more science than Tall empires, more than enough to counteract the penalty. Happiness is far easier to deal with through ideologies, especially in Order and Autocracy, and settling late is no longer a terrible idea because of trade ships. In some ways, wide empires are better than they've ever been, even if ICS has been nerfed into the ground. Warmongering penalty was reworked to make it LESS stupid, and less exploitative -- in fact, the intention was to make it better than it was before, so that trading the AI one terrible city and then declaring war wouldn't be a thing anymore, and so you can't just goad the AI into declaring war, then take all their cities. Declarations of war are now worth very little. Unfortunately, it's far too strict, especially if you conquer from tall AIs. Fortunately, the devs are working on it, and one of the things being addressed in the Fall patch is the warmonger penalty.