I'm not sure "the AI is ineffective" makes the AI computation easier, and that therefore makes a substantial difference on a range of hardware vs. better lategame optimisation over CiV.
I mean, we're all guessing at the end of the day, but I feel like you're working backwards from the conclusion of the AI being poor.
Why then babylon has an 'Air superiority' agenda, then builds planes ( only civs basically to do it) and then do nothing with them?
Why there must be an 'Air superiority' agenda in the first place???
AI is not inherently poor, obviously, when you have a science OP civ like Babylon, with planes, and cities with their own defence (starting from civ 5)
why should the AI build units? Not for defence. Only for attacking another AI civ with inexistent units.
And never attacks the human player that has at least some basic defence units bc it is just not worth the effort.
Victory is much more simple to obtain other ways. Only when one human player get near some victory type, it starts doing some spying.
Playing Emperor, Babylon beefed with air units, 10 techs beyond me, and no matter what, it won't attack me.
AI is either too smart, or being dumbed down deliberately, bc micromechanics are now so much more important to the various
victory types, that military makes no sense. Of course is being dumbed down bc Babylon with its chariots can steamroll everyone on the map
and the game would end at turn 50. But that should be the norm.... every civ should steamroll its unique unit and try to conquest the stronger
player, in order to try to take the lead... but this NEVER happens in civ 6.... it's always the weaker to be attacked... bc, again, it makes sense
with current mechanics, to just try get more economics going...
To me AI is poorly designed, it's to that is inherently 'weak'...
If in Civ 3 or 4 a human do not build a strong defence force, it gets sweeped, playing warlord... that is the way... or it was...
And playing Tethurkan, 60+ civs mod in civ 3, turns would take ages at one point, before communism, bc of so many unique units...
my Athlon from 1999 was burning hot during those gameplays... thousand of units....
now AI do not build units basically, and yes, it's considerably faster bc of poor Ai... again, not saying Ai is 'stupid'... it's the game broken agenda tree that requires Ai to be 'micromanagement focused'....