Can we say that modern AAA graphics is way more complex than a single human can handle unless perhaps he started graphics programming many years ago?
No, but it is a full time job. It's getting much more complicated. Here's an hour long talk on how Unreal Engine 5's Nanite works.[1] This is a huge breakthrough in level of detail theory. Things that used to be O(N) are now O(1). With enough pre-computation, rendering cost does not go up with scene size. See this demo.[2] You can download the demo for Xbox X/S and PlayStation 5, and soon, in source form for PCs. Exp…
Fusing that with what Epic is doing is basically going to enable even more detailed gaming worlds where a lot of the content is generated rather than designed. Flight simulator scenery is bottle necked on the enormous amount of triangles needed to model the entire world. Storing them is not the issue. But rendering them is. Removing that limitation will allow much higher level of details. X-plane is actually pretty good at generating e.g. roads, rails, and buildings from open street map data but the polygon counts are kept low to keep performance up. Check out e.g. simheaven.com for some examples of what x-plane can do with open data. Not as good as what MS has delivered but not that far off either. And they actually provide some open data as well, which simheaven recently integrated for x-plane.
Flightgear actually pioneered the notion of streaming scenery content on demand rather than pre-installing it manually. X-plane does not have this and MS has now shifted to doing both installable scenery and downloading higher resolution stuff on demand while you are flying.
Once you hit a certain size, pre-installing all the content is no longer feasible or even needed. Once these worlds become so large that exploring all of it would take a life time (or more), it's more optimal to only deliver those bits that you actually need, when you need them. And doing that in real time means that even caching that locally becomes optional. And even the rendering process itself does not have to be local. E.g. NVidia and a few others have been providing streaming games with cloud based rendering. That makes a lot more sense once you hit a few peta/exa bytes of scenery data.
Another interesting thing is generating photo realistic scenery from simple sketches with machine learning trained on massive amounts of images. This too is becoming a thing and is going to be much more efficient than manually crafting detailed models in excruciating amounts of detail. MS did this with flight simulator. Others will follow.
Interesting times.