So, I'm not @JonM but I think I see where he's coming from.Let me ask you a few questions:
* Do you think what you're responding to is your cognitive orientation toward how this is operationalized (rather than an objective quality...or do you think your cognitive orientation toward how it is being operationalized is you detecting actual signal of an objective quality)?
* Do you think you're responding to your sense (due to the experience you're citing above) that players cannot play skillfully through a mystery and reveal a truth about the "reality" of the shared imagined space that was hitherto unknown?
I think it starts with a recognition that the primary (most-frequent) pleasures of whodunits (or, if you want to be more highfalutin, mysteries of ratiocination) are at least somewhat different from those of TRPGs. This is a thought I've expressed before, but briefly the pleasures of a whodunit are A) beating the detective to the solution and/or B) watching the detective figure it out (or, plausibly, following the detective's explanation of how he figured it out). Pleasure "B" above isn't a viable pleasure in TRPGs, and pleasure "A" can possibly be simulated if you have some sort of time constraint in-game--but that still involves "figuring it out."
Whodunits where there's an expectation that the players are going to solve the mystery do not seem as though they are compatible with playing Story Now. What seems as though it would happen more in a Story Now game is that the players would write the mystery's solution. Even the process you went through of filtering the possible (plausible?) solutions and eliminating them one by one, is more the latter than the former, I think.
At least, that's the thinking from people who don't intentionally play Story Now games.