The only problem I see with dropping posts from indexes or visibility on age is not all topics move at the same rate. For example, a JS front-end topic might be

The only problem I see with dropping posts from indexes or visibility on age is not all topics move at the same rate. For example, a JS front-end topic might be dated after only a year, but a question about some systems programming issue or slower moving topics might still be relevant after several years. Yesterday I was searching for utilities to find and remove duplicate files and a stackexchange question was returned. I was skeptical of the results since many were dated from 2011-2012, and I think they indeed were out of date, but sorting the comments by most recent lead me to jdupes which appears to be the best current solution for that problem.