I just watched 1917 again last night.
Obviously, it's a technical achievement. I don't think anybody would deny that. I still maintain that it's a masterpiece. Some people do deny that.
The thing is that I'm realizing that I'm more fascinated with WWI history than nearly any other conflict with the possible exception of the American Civil War. I'm simply happy when WWI actually gets some attention because it's a deeply important and tragic part of our history while being more philosophically complicated than most wars. The Germans weren't Nazis in WWI.
It's true that WWI doesn't lend itself to cinema in the way that almost any other war does. Trench warfare doesn't help to check the spectacle box that Truffaut viewed (correctly) to be essential in filmmaking. So, WWI is usually a backdrop to another story or philosophical battle like in Legends of the Fall or Paths of Glory. Even Gallipoli, which is a great film, took it's time before actually examining the war.
It's rare to find a WWI movie that's really about the war. Movies like All Quiet on the Western Front, The Big Parade, War Horse, and 1917 are rare to come by.