I do not see how you can tie tropes to railroading vs agency. Can you explain that?
Lets take some of the tropes from the first post
- The world is full of horrible monsters, dastardly villains and angry gods, many of whom dwell in deep underground fortresses full of traps and minions.
Why are the monster there? What do they want? Can their deep underground fortress even sustain a monster population? How have nations changed when being constantly threatened by monsters?
Most of those questions are unanswered, because answering them is hard and the answers would result in some big changes away from the usual representation of the setting, possibly violating other tropes. Monster are there because its a trope, you are heroes, go kill them because <quest> sends you into those dungeons. Thats how you get XP and equipment.
- Alignment is real and an understood part of the philosophy of the world.
This again would have a huge impact on society works when you think about it. Screening the alignment of important people would be normal which also would make priests more important compared to normal RPG games. But better not bring that up as it would shake the usual representation of settings to its core. Just nod and accept it is a plot device only used in very important moments and then forgotten.
- The most powerful magical items in the world are beyond even those superhuman heroes. In fact, the world is full of the ruins and detritus of an age of immense power and apparent malevolence.
From fantasy to scifi this is so very common. In the past there was a very powerful A which made things unachievable today. And when you want the best X possible you do not seek out master craftsmen, try to curry favor with nobles to gain access to them, etc but you go down some ruins, kill the monsters there because of course they are there and pull it out of some rubble or hoard because you were apparently the first one who thought of that despite the world being littered with magic items in ruins. It is all so very predictable.
And it also raises always the same expectations. So if you happen to find a lost legendary sword and it turns out it is a +2 bronze short sword, because that was the best they could make with their metallurgic and magical knowledge back then players would be upset because the expectations through tropes is old & found in ruins = better what you have now.