As is the the Total War series in general, even if I don't like naval battles that much, but hey that's what superior numbers and auto battles are there for.

Total War is a technical miracle. I've yet to see any other games have so many animated units on screen in a battle at once. Other games don't even come close. It creates an amazing atmosphere.

Have you played Mount & Blade: Warband? Some random video I googled with big battles (500 units active) https://www.youtube.com/watch?v=3onap7r0ZUM

Yes and no. I followed the first Total War game (Shogun) from before it's release and it was just sprites on a 3d board. When it went full-3D it just used batching. True, they always slightly pushed what graphics were capable of but not necessarily to the same degree as the FPS or RPG genres.

But thousands of animated characters on screen is pushing the graphics. You can't really do the same in a standard way with an off-the-shelf engine. You put 500 animated characters on screen in UE4 and everything is going to crawl to a halt.

RTS games even today limit players to ~200 pop each.

The amount of units in Total war has basically not been going up, because they value animated units to much.

You are still playing with low 1000s of units, and this has been the case for a decade. The AI is also not really much better.

Even on strategy map level it has been simplified.