Claim 1: Knowing the solution to a puzzle means it is no longer a puzzle. The enjoyment of figuring out the solution is gone.
Claim 2: Some stories have puzzle elements that are a significant part of the appeal, eg. riddles (intensely so) or whodunits (not as intensely so).
Conclusion 1: Some stories are adversely affected by knowing them in advance.
Claim 3: Puzzles can be good.
Conclusion 2: Stories that are adversely affected by knowing them in advance are not inherently bad.
Claim 2: Some stories have puzzle elements that are a significant part of the appeal, eg. riddles (intensely so) or whodunits (not as intensely so).
Conclusion 1: Some stories are adversely affected by knowing them in advance.
Claim 3: Puzzles can be good.
Conclusion 2: Stories that are adversely affected by knowing them in advance are not inherently bad.
Any absolutist statement about art is bound to have counter examples.