I agree very much with this. The tactical AI still isn't brilliant, but since the last couple of patches I've seen the AI throw multiple sieges on city states where they will bring a good number of melee or mounted units and will actually deploy and use siege units. I've seen several city states taken down by a combination of a handful of Longswordsmen or Musketmen and two Trebuchets (I use the Steel and Thunder mod that adds these units). I've also seen AI use combinations of land and sea units to put a city state under siege.
That said, the AI still has some severe shortcomings. They can overpower city states by out-teching them, but they generally fail against major civs on their same tech level. To be fair, this is as much a question of walls being too strong (imo.) as it is a question of the AI being bad. They also seem to fail at regrouping and falling back when their initial assault is dismantled. These are situations where we still see the famed single unit rush, or even rushes using civilian units. Again, this is as much an issue with the AI as it's a question of game design: The fact that producing new military units take at least a handful of turns, and often significantly longer than that if you don't have a production-focused city, leaves the AI extremely vulnerable once you have cut their gold reserves and supply from them.
Wrt. district placement, there has also been improvements in this area. I actually see some decent district placements fairly often. They probably still don't understand to buy tiles to get optimal placement, but the nonsense placement we saw in the early days seems to be gone. I think the issue is not as much that the AI places their districts badly as it is that they generally build too few districts and/or the wrong ones (yes they now build many campuses, which actually helps them keep up in science, but they sure do love their encampments and holy sites still, not to mention entertainment complexes and renaissance walls (which may actually not be a bad priority to help them survive)). Again, I think their tendency to wasting military units futilely ends up acting as a major production sink that draws away production from more constructive elements like districts and buildings.
I have just started playing civ 6 again and starting to wonder at what point does the AI actually build any military usually?
I started at a lower difficulty to learn the game more and built my way up to emperor now. Playing huge maps with 12 civs on epic speed there only ever appears to be one civ on a map who actually has a military at all. In my current emperor game in the information era i have 3500 military score with what i would class as a bare bones army (from playing vox populi), america has a military score of 1100 which appears to mainly consist of rangers and heavily outdated cavalry units from the visibility i have and all other civs have less than 100 military score which from my understanding of the military score is around 1 unit each with 5 of those civs having over 10 cities so it is not like they can't support a large military.
At one point mid game congo did appear to have a reasonable army (didn't actually check military score at that point and only assumed based on taking the city state early on and the units i got visibility on from them attacking my allied city states) and had taken a city state it had settled around. We ended up at war as part of an emergency but there were (my) suzeran city states between me and him and they just ripped his army apart, even going so far as to take one of his border cities and raze it. We ended up in phoney war for around 40 turns while i moved my army to him and built more units expecting a difficult fight and when i decided to invade him i only saw one unit which he built while i was attacking so it appears my city states had wiped out his military and he never rebuilt them?
While i have seen a few city states get conquered, as a whole it would seem city states are much more capable of defending themselves and attacking threats than the civ AI's do, which i guessed was down to resource availability restriciting the AI from upgrading to current units but tis is still happening with the more resources mod.
I have never seen an AI scout or any other unit apart from a builder appearing to explore at all. I have only ever seen one AI (none CS) ship and that was built by Kupe who is a naval based civ. In fact the only difficulty i have had with any combat is when during my congo war, in a single turn their cities/encampments went from 60 strength to 80 strength which (from my understanding) is probably because they built that one current era unit as city strength is based off the strongest unit you have trained(?) so their cities could actually kill my units.
As this game is in the closing stages should i just jump straight to Diety or does the AI actually step up on immortal?
As a side note the AI seems extremely lacking in the builder department. During early scouting in my current game i discovered england and india and it appears england had taken one of indias cities before i met them both even though england had a military score of around 50 and india were currently the leader with over 500 military score ( i assume england just about captured the city while wiping out it's own military and india just gave up?). To the point, i noticed that a number of tiles had been pillaged during this war...around 150 turns later i had visibilty on these tiles again and they still were epillaged?!
On a similar note, when conquering cities i tend to have to send in a troop of builders, not to repair tiles as almost not are improved but to simply do basic improvements of even luxuries or strategic/bonus resources never mind farms, mines or lumbermills.
I do occasionaly capture a builder but this is usually wondering around in no man's land although very occasionaly i capture one in the AI's territory.
As an additional comment, as i usualy see when discussion of poor combat AI comes about there is inevitably discussion on how 1UPT was a mistake and we should allow stacking as the AI could deal with that much better...can i just say that stacking is just papering over the cracks of poor design and implementation. 1UPT doesn't break the AI it just shines a bright light on the traditionally sloppy design and implementation that is traditional with civ games as AI can handle 1UPT perfectly well and in an effective and dangerous manner if programmed well enough. i.e. as per the great AI the vox populi people have created where the AI can attack and defend on a huge front while protecting vulnerable squishy units and can do so with cause. My most epic brown trousers (seriously impressed with the AI) moment of any 4x/strategy game was when a 20+ fleet of ships appeared out of the fog of war off my coast protecting a sizable invading army. On the ther foot a seaborne invasion, even over a small straight and with overwhelming force can be a prolonged and difficult endeavor as the AI defend the coat effectively, not allowing a foothold and cycling damaged units out to heal rather than just letting me pick them off peacemeal. A recent vox populi game i wanted to invade a AI over a 2-3 tile straight. The first 50+ turn war ended in stalemate. The second war i had to sacrifice a number of units to eventually take a coastal city and had to expend a great general to build a citadel to defend it from being recaptured and even then i had to slowly roll the AI back as they would kill any unit which exposed itself.