Conquering cities in Civ5 might be strange but it makes this game great.
Hello. Civilization 5 is one of my favorite games of all time and Civilization 6 was a complete miss for me. Two,,strange and controversial" mechanics from Civ5 which might be a little strange provide a good balanced experience. I am talking about happiness and the fact that after conquering a city all but 1 citizen die and all the structures are destroyed. It is extremely strange and unrealistic but... it makes this game better because it unables snowballing. In Civ 6 the more cities you conquer the stronger you become but in Civ 6 conquering cities is mainly a cost, a negative to your economy. You don't get any economical benefits because all pops and buildings are gone plus the occupation decreases your global happiness. Conquering cities is not about growing but about destroying the danger of other countries.
Settling a new city would be a better idea but at some point there is no more free space, destroying the conquered city and settling a new one on its place would remove the occupation negative but raizing cities is a warcrime and AI would imidiately hate you. Fighting enemies is not a way to grow, it is a way of danger prevention and in order to grow you still need to manage your country well and not fight others. After some time the conquered cities will start to provide economic growth of course but at the beginning it is more of a negative.
This mechanic might be illogical but it has created one of the best antisnowball systems ever.
In the case of happiness I don't even know what was the issue. It is a very logical and fun mechanic keeping empires in check. A very balanced system.