The main purpose of barbarians is to force everyone to have some investment into units in the early game. Otherwise a Civ with a remote or easily defendable starting location could gain a giant snowballing advantage by just ignoring military altogether.
Nah, we won't.
The newbies and critics will always play the game on Prince difficulty. Coding an AI that gets "organically" harder with difficulty (better tactics, smarter decisions etc.) would in effect mean making the best AI possible, then intentionally dumbing it down for lower difficulties. From a publisher standpoint there is zero reason to do that. You'd be presenting your product to the critics, e-celebs, influencers and just overall new players in a state with worse AI than what you're currently capable of shipping. It would be a retarded business move.
Civ's AI relies on cheating buffs because writing AI actually smart enough to rival a human player in a game as complex as Civ is far beyond what any gaming company has money for in their development budget. Even more importantly to get it to run on the PC of the average customer (or more critically, consoles) would be impossible without loading times so long they'd turn off all but the most hardcore fanatics. Again, not a worthwhile business move.
By the way I'm saying this as someone who plays Civ 6 rolling "random" to everything and can still beat the game on Deity 4 out of 5 times, despite role playing and fucking around (and being drunk most of the time I play the game). I never needed to read any strategy guides or meta posts to achieve this level of "skill". Deity is not as hard as you might think despite the insane starting buffs the AI receives. As long as you don't get steam rolled early on by something you can't do anything about the difficulty quickly eases off, which is pretty poor game design in itself too.
