An aspect or feature that I think wasn't mentioned yet: Many (bigger) games use a rubberband AI. So on easy modes it's tuned to always lag behind you, and even "normal" means there is still a slight lag to cater to gamers' psychology. So AI difficulty settings shouldn't be done with resource handicaps or bonuses (alone) (but surely could be another optional setting). Basing difficulty setting mainly on this will mean drastic changes whenever the actual AI algorithms are improved. That's really not a good "dependency". (Also, what wasn't mentioned yet, how good the AI is in 0 A.D. also very much depends on the map, in my experience. With special resource situations, usually scarcity of wood, it has great problems.)

The problem would still be the same: only one route is worth using at a given time. Retreating to the next longest route is putting a band aid to an exposed femur fracture

Congratulations, you are very talented! Obs: The correct link uses lowercase letters. https://www.artstation.com/margab

Good point, thanks! Sorry for my ignorance on MacOS... happy that you are testing it!!  

Si vis pacem, para bellum. (That phrase fits well)