Isn't one of the main aspects of immersion that it feels like the real thing?

That's far harder to do right than graphics and it's going to have a bigger impact on how immersive the game is. You can always improve graphics down the line but getting the mechanics and handling right is a lot more important and will be a lot harder to change later on.

I got absolutely immersed in Indianopolis 500 back in the day[0]. The graphics were pathetic by modern standards but the long races felt like you had to manage a variety of things (tire wear etc) and you really had to commit to it. So I would agree graphics are secondary to the immersion experience.

[0] https://en.wikipedia.org/wiki/Indianapolis_500:_The_Simulati...

Whether it looks like the real thing certainly also plays into whether it feels like the real thing.

Oh absolutely however the "feel" matters far more. If the graphics look super dated or minimal but it plays great, you'll still get lots of players however if it looks stellar but plays poorly, you won't retain very many players.

I watched my younger cousing playing the new Rainbow Six. Compared to the fist one, they are completely "arcadized". Just a narrow step down from Urban Terror on "cinematic gameplay". "Realist", but not so much.

Graphics, yes. But the actual gameplay... a joke compared to the first Rainbow Six and tactical matches on SWAT3.