A WikiReductionist believes that, for Wiki quality to recover and then increase,
"Wiki could use quite a lot more deletion." -- StephanHouben, DeleteAndArchive
See WikiReductionists for some history.
Counter viewpoints: WikiConstructionists, GentleReductionism, WikiFilterist
On the other hand, Wiki has had TheAdjunct as a SisterSite since August 2005, specifically to take the burden of OffTopic content from here. See MovingPagesToTheAdjunct.