As someone that first played it on a PS4 and then again recently on a maxed out PC, I can confidently say the immersion was superior on the better machine. In fact, I was salty that I first experienced it on such a gimped device.
But I am saying that it’s unnecessary for a deep immersive experience. I was equally immersed 20 years ago playing Gothic and Oblivion as I am playing recent games, graphically speaking. IMHO the differences only become apparent if you play the same game with different visuals, as you did playing RDR2 on PS4 and again on PC.
It’s also worth remembering that the vast majority of players also don’t have access to a maxed out PC.
But you wouldn't be immersed on Gothic now. By playing gothic you set a new bar for yourself and that's how the industry works. Audiences everywhere get more and more sophisticated so much so that what worked back then won't work today and what works today won't work tomorrow. Can't wait until the time RDR2 becomes an "old" game with shitty graphics.
Rockstar knows their community. They spent around $1 in marketing for every $1 spent on the development of the game itself, totalling around $500mil, and the game paid for itself opening weekend with over $700mil in sales.
The studio has managed to master this sort of high-fidelity development while fully recuperating all costs, and fostering an incredibly loyal fan base. (Personal data point; replayed every single Rockstar title last year)
You cannot criticize such a company for delivering high-fidelity projects and pushing the edge. (You can criticize their working environment, however)
And without such companies blazing ahead, we wouldn't be currently undergoing a revolutionary phase in tech history as we explore the power of massively-parallel, computationally-intensive AI algorithms.