Is that any weirder than not knowing why the runes were created?
I don't follow.
When attention is paid in the play of the game to the runes,
the reasons for their creation emerge. As the anecdote illustrated, that took place in a way different from
the GM making an authorial decision or
the GM reporting an earlier authorial decision. Attending to the fiction yields answers about it, via the relevant process of play.
Whereas I'm saying that, if I am playing a Star Trek game, and my character sits down with your character to explain the special relativity thought experiments, we
don't know or work out what my character says to yours.
The general point I was making is that
departures from the reality of physical law, in a fiction, will inevitably produce tensions, and ultimately contradictions, if we focus our attention on those features of the fiction that constitute the law-breaking. How does a dragon fly? How does light behave in Star Trek? How do Batman's joints and muscles survive the forces that operate on them when he catches himself on his swing lines, cape, etc? How does a "sword" the size of a pin behave just like a rapier? And so on.
This is a particular point of vulnerability in a RPG because in RPGs, unlike in fiction which permits more author control and editing, it is harder to stop situations that engender these sorts of tensions emerging. The author of a fantasy novel can simply refrain from having any characters perform physical and biomechanical experiments on dragons. But what happens if the players in a RPG have their PCs do such things.
As I said earlier, I believe that Star Trek has never had its characters discuss special relativity as their ship accelerates to warp speed. But what stops players having their PCs do this?
Likewise with the mouse-y rapiers - can a player have his mouse PC try to investigate the tensile etc properties of their rapier?
I posted examples upthread from my own sci-fir (Traveller) RPGing where we, as a group, reached consensus and compromise on some of these sorts of issues. I also posted, and continue to think, that achieving that sort of consensus/compromise can be harder if the players are trying to beat the scenario or solve the mystery - because that puts more weight on them making their own inferences about the fictional facts, but if the fictional facts ultimately entail contradictions then there is risk of those inferences breaking down.