I'm under the impression that the game isn't struggling because of having indecent graphics cards, but because of CPU optimizations for such a huge scale game.
For example, I'm running RTX 3090 Ti and at 1440p, my game runs at 100+ fps at max on average (including any big dips). While the GPU itself is being used at around 60%.
It's kinda like having a massive mob farm in minecraft and once close to it and looking at it, you'll have your FPS consumed heavily compared to when being away from that. I see that it's gotten better over a number of alpha releases.
You're right, implementation would be a huge player, but I bet they would make it a selectable option rather than going the Metro Exodus way.