and btw, the pc version of witcher 3 got the downgrade too? why? why not release that version on pc?
What they usually do for a vertical slice is that they take one place and bring it up to the visual standard they want to hit. It is done to represent a vision or where the game is going.
What usually happen then is that a bunch of level artist and designer spend more time than usual polishing this particular area. When the production start afterwards, the standard inevitably get revised (ie: down) because of production issues, performance issues, etc, etc.
When the game get first shown to the public they show this vertical slice, the visual target dreamt by the Art Director. Then reality takes its toll and production push it down.
To get back to why it's not on PC, it is probably because stuff only get done once for every platform. The upgrade are stuff controlled in the rendering, light effect, etc. Having more objects, more npcs, everything in world really forces the level artist to do the job twice (One for each version), or at least keep them relatively close to each other.
They already don't have time to do everything once, asking them to keep up to date 2 version is insane. They will always calibrate to the lowest common denominator (ie: the least powerful console.).
I don't like the term lying because it implies that the devs don't want to the world to look like that.
That they purposefully show a false game that they knew at the time that they were never going to hit that, not even on PC.
That's a gross mis-reading of intention, they show what they have
at the time.
There is no "final product" that you can take a piece of as a teaser.
There is only a WIP product, which only a bit is polished enough to be shown to the public, most of the game being white boxes and dreams in devs heads.