Okay, returning to my comment about “I had a problem, therefore a problem exists”. What I should have said is that “I had a problem, therefore a problem exists with the game” is often mistaken. in my personal and professional experience, the number one reason a game session goes badly is thst it’s being played by human beings. Human beings are subject to fatigue, intense emotions (good and bad - being in the midst of falling in love can be as distracting as being stuck with a situation that makes you angry every day), low blood sugar, high blood pressure, confusing elements from similar but distinct games, chronic pain and other symptoms of illness, anger and fear and misery over your social situation and political developments, concern for the ailments and suffering of people who matter to you (along with pets and such, too; the brain responds to the loss of a loved pet the same way and with the same intensity as to the loss of a loved human being), allergies, and more. All these things can and routinely do make game sessions burn down, fall over, and sink into the swamp. But the problem was not the game.
We tend not to talk about this very much, and particularly not as an aspect of game design, in sort of an equivalent to evaluating character power in white-room abstracted scenarios. There are things games can do to help out some players. Monte Cook‘s sidebar cross-references, Arcane Library’s self-contained spreads, good indexes, and so on - nothing works for all people and all sources of trouble, so some people will continue to have problems, but it can improve some things for some people. But there will continue to be bad, unsatisfactory sessions that are not the fault of the game.