Your AVX statements are out of date. Nowadays AMD supports AVX-512 but Intel removed support from the consumer line (only workstation and enterprise products support it for the last 2+ generations)
Not really. Monitors do poorly at lower refresh rates (anything under 50Hz, hence HDMI2.1 for example only doing 48-60 on 60Hz but on a 120Hz it can use LFC to multiply lower framerates). If you drop to 47FPS on a 60Hz VRR display you lose VRR or get other issues (flickering, persistence, etc). If you drop to 47FPS on a 120Hz VRR display it doubles it to 94 and you're still smooth.
Because Stardust said "Get a Steam Deck and then you'll see why" which makes no sense in the context of Denuvo DRM, hence it is most likely Stardust confusing anti cheat issues for DRM ones. Not that hard to figure out.
Other than the original Dark Souls port none of their games have been unplayable on PC. Tons of major UE4 games have had constant stuttering issues however.
I left 6 years ago and don't regret it for a minute.