It is that the AI is the hugest hypocrite ever and gets their panties in a bunch for going wide. I don't think that all the nerfing to wide civs, science, culture, unhappiness, make wide empires worst than the 4 city tradition this game wanted to shove down our throats. Instead the true deathknell to wide empires is how the ai overestimates their power so they gang up on you when I go wide. "They think you are settling cities too aggressively" seems to be one of the biggest and potent negative modifiers. I see Ais flip from "friendly" to denounce, to war, within 10 turns EVERY TIME I see that modifier go up. I don't see the AI gang up on me very often when I'm 5 or 6 city tradition but good god do they hate it when I'm wide. The AI is built to not see the danger in a much stronger tall empire.