The question of AI competence is only really an issue for a very small subset players, which is why they don't invest in it too much. While it's easy to say "just make it a toggle", that would be a lot of development time spent frivolously. It's easy to forget that the average player only plays a video game for a few dozen hours if that. Someone who spends hundreds of hours on one video game will notice all the quirks and balance issues, which can be annoying, but at that point you've pretty much exhausted the entertainment value offered by the product. It's understandable, if frustrating. Frankly, this is something that the community is better off creating themselves. The AI+ mod is pretty good, and maybe at some point a Community Patch project will begin for Civ6... most likely when it's feature complete. No, it is not, especially without hundreds of hours in experience and the use of exploits like chopping overflow.