Haha, as I said - each to his own. With mods (imported faces, camera and lighting mod mainly) I personally think 16 looks less cartoony and more realistic in its style. It's just my opinion, I don't mind if you don't agree. Saying 'it's just not true' doesn't make your opinion more of a fact than mine.
For me, the colour palette and the textures in the pitch itself is a big part of it - and I think it has dropped in quality in recent FIFA titles. I also agree the Frostbite engine hasn't fundamentally changed, but there are still differences. I'm not talking about every aspect of graphics -of course more recent titles has its advantages, I just mean overall looking at the game as a I play it.
Here is 16,17,19, 21 compared all on the same conditions, same time of year. For me, 16 looks more realistic and 17 is next. I do agree there is a slight yellow tint on 17 that could be improved, I might look at that in a lighting mod, but it still looks less cartoony than 19 and 21 in my opinion.
FIFA 16:
View attachment 97438
FIFA 17:
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FIFA 19:
View attachment 97442
FIFA 21:
View attachment 97440