I noticed that this question (about shortening existing solutions to the Rubik's cube) was downvoted and migrated off the site. To me it seems like an on-topic question. After all, the help center says:
If you have a question about [...] A specific method of solving a type of puzzle [...] then this site is the right place for you!
And the sidebar when asking a new question asks (emphasis mine):
Is your question about creation and solving of puzzles?
However, a highly-upvoted comment on the question read (Not the exact wording, I can no longer get to the original question.):
I'm closing this question as off-topic because it is not a puzzle.
This would lead me to believe that the community has decided that questions about puzzles are not on topic, only actual puzzles are.
Has the scope of the site changed to exclude questions about puzzles? Should we update the help center &c. to reflect this?