I feel like it is pretty indistinguishable in STS if you lost because you made an incorrect decision somewhere or the run is unwinnable. Something like Zelda or Metroid you can reach a point and the game has some kind of obvious solution or key you need. STS has too many solutions to the problems of what you face and no way to go back and recheck things. The fact that it is almost impossible to find an unsolvable STS seed seems to indicate that their approach is pretty good. Player frustration in STS except for the tiny number of runs indicated in this post is entirely skill based.