Graphics have kind of flat lined as well take this for example - https://www.youtube.com/watch?v=xQKcTwq_4lk&t=1011s (which I was talking to a gamer friend about on discord this morning) that's a game from 2017.
While there have been some slight improvements since they'd already reached a level where for most games they were already good enough and so the game play becomes the most important thing and that hasn't really changed much in a decade.
With one exception (Arma Reforger) nothing I play was released in the last 6 years.