This is a pretty terrible idea. I've run a wiki at work and a lot of the information is outdated but a lot of it is also still really relevant even given that

This is a pretty terrible idea. I've run a wiki at work and a lot of the information is outdated but a lot of it is also still really relevant even given that the page has not been touched in 3-5 years. Somewhat wiki related but on the software side - I created a very basic plugin for wikimedia that solves a specific problem and because I did not have any commits in my github repo for 3-6 months they flagged my plugin as "do not use" and "unmaintained". It was frustrating to put something together in my free time and to have the community basically shun it because there were no new features I could think of to implement. I think documentation is the same way - creating friction by deleting, hiding, or even obtrusively flagging pages as "old and invalid" can make people not want to use your system.