>>317764 (OP)
>Are gamers born retarded or are they just well-practiced?
My guess is that it's the latter, both from my own reading and from what I've observed.
Watching streamers play Peripeteia's tutorial level and discussing what I observed with the game's former level designer (we go back a long ways) was interesting. Initially I noticed that experienced FPS players were noticeably worse at navigating the levels than 3DPD and people who played very few 3D games, which was really weird to see even after I realised what was going on. Basically, the former weren't actually navigating levels the way they would a real-world 3D environment, but had basically conditioned themselves to be pulled around video game levels by "subtle" level designer tricks, and were utterly lost if a game level had less of these than usual. Most of these tricks are borrowed from Disney theme park design, which is explictly intended to magnetically pull a fat tourist around a theme park with zero conscious effort. In the absence of these, players would do things like stare directly at a giant glowing building while saying they had no idea where said building was, subconsciously assume they couldn't climb over railings even though the game was built around climbing mechanics, and generally wander around in a daze like headless chickens.
What was really interesting was that after some time of this, some kind of mental switch would flip, and players would suddenly find they understood 3D spaces better and could navigate just fine. The question became: how could the level designer help the player flip this mental switch as soon as possible? What he settled on was spawning the player inside a pit, thus forcing him to learn how to actually look at the environment and learn the climbing mechanics as soon as possible. This would also gatekeep anyone too stupid to escape the pit.
The funny thing is that this largely worked. The amount of level design complaints the devs received plummeted.
All the above is especially ironic when you learn that spatial memory is something humans actually have an innately high capacity for. We're really good at things like perceiving and remembering room layouts, and it's a skill that comes so easily to most people when it's actually trained (aka when we aren't letting Google Maps route everything for us) that much of classical memory training is all about exploting this. It involves techniques like mentally tying datasets to objects in physical spaces, and remembering them by taking an imaginary walk through the location.
This is the exact opposite of the basic underlying assumption of modern level design, which is that people inherently have the memory and spatial awareness of a goldfish. The modern level designer believes that people must be coddled, rather than encouraged to bring out and develop their natural abilities. That's not to say that a gamedev has to go to the extremes of the example I gave (the guy's a massive urbanex sperg who wanted to capture that experience in a video game), but I do believe that a lot of game and software design is effectively backwards, as much of it is about perceiving, thinking, and remembering for the user instead of helping him to become better at doing these himself.