[BlargMcLarg]

>Compare that to Elden Ring, which has difficult boss fights but otherwise isn't any harder than any level of one of those old games.

I haven't played Elden, but for comparison's sake, I haven't had any trouble picking up SMB3 blind nor did I find any of the levels individually more difficult than most high rank monsters in Monster Hunter Rise. SMB1 definitely isn't a difficult game either bar a few specific levels, 8-3 being the most notorious.

The biggest thing I see people struggle with is patient, reactive and/or predictive gameplay. Any game with counter mechanics relying on tight windows showcases this: most people either fail to utilize them or simply don't bother. Let alone emergent counterplay. The other part, you can't just statstick your game through most older non-RPGs, where newer games provide you with many more methods to allow more failure.