I think IFWiki should have the confidence to operate on a sort of “meta” level where it actively tries not to replicate anything that is or should be elsewhere. I think that would entail some deletion of content (although not deletion of all game pages… I agree now and feel like such a Philistine).
So for games, it should aim to have links to IFDB, CASA and elsewhere, but not links to reviews (for example) if those belong better on IFDB etc. If IFDB or CASA has an API maybe it could automatically take a summary from there (and attribute it clearly).
For documents like that Ron Newcombe guide, it should link to but not reproduce them.
Even uploads for historical interest/archival maybe should be uploaded to and linked from IFArchive rather than uploaded to IFWiki.
With the out-of-date information that is presented as if it is in date, maybe we need to start again at the top of the page and keep the old table (or whatever) at the bottom of the table for reference, maybe temporarily.
This forum as a source of information too, including it’s own wiki posts, so maybe IFWiki should link to relevant topics here, like the big Inform 7 one, Inform 7 documentation and resources, or even smaller ones like List of glulx/.gblorb interpreters. Alternatively, maybe these forum-wiki pages in particular are cases where the forum should bow to the wiki as being the more appropriate place for the information.