On of the "quality" discussion we tend to come against again and again seems to be related to a basic 'conflict' we have:
SE is a site to create permanent value (normally in form of searchable Q&A)
Puzzles are fun and entertaining.
If we concentrate on the first too much (we had that!), we kill the site by driving away people and generally ripping the heart out of PuzzlingSE. (...been there. No need to go there again.)
But most of the 'quality' problems of PuzzlingSE comes from concentration too much on the second. Why? Because a lot of things can be fun and entertaining - even related to puzzles - but not all of them are a good fit for this site! (Jokes, trick-questions, little-effort time-waster games, social-media like puzzle games etc...)
I have been think lately, how we can reduce (if not eliminate) such content from this site without being too harsh or overdoing it, and one thing which appeared to me was, that we do not have an appropriate close-reason which summarizes this problem. Why not? Because other SE sites don't need it - it is part of the principle site model and goes without saying. But Puzzling.SE is a bit different, so I think the following close-reason might be useful (feel free to adapt):
no lasting value
This question/puzzle does not seem to create lasting content value. Puzzles/questions (and their answers) on this site should remain valuable even if 'found' for the first time in future (months/years). 'Game' like content or other strictly presence-centered postings without lasting extra-value should not be posted on this site. Note: It is sometimes possible to edit (answered) puzzle-questions in away that the remain valuable for future readers.
My phrasing might not be ideal, but I think I've made my point. If everybody checks puzzles/answers with "future-value-glasses [TM]" on ( i.e. imagine some non-member finding this puzzles in 3 years time from now - how valuable would it be?), then it becomes pretty clear which postings are "good" and which "aren't". Several of the low-quality postings ( challenges, find 'shorted/longest' etc. ) are simply only "fun-as-long-as-engaged-with" but afterwards they are dead meat.
Some of them, can be edited to become of value - i.e. I find it good to have a source of creatively discovered words/sentences which share a special property etc. - put I think it should be a requirement to edit the content (and final answer) to be of a sort useful in future. If nobody is willing to do this, the question should be closed/deleted and the close-reason above would be the most suitable one.
This is of course a discussion. So I'm curious about other opinions.
I maybe should add that any puzzle with (or still without) a valid, explained answer is clearly a thing of permanent value! So most (or at least many) puzzles on site do absolutely belong here! Still, some of them could need some "after-solving"-edit, too.