Something that I think would help a lot would be if we could tag links somehow (not just on the page, but from their menu) with an indication of how old they are. Like maybe change the template so that it shows how old each page is, blog style, before you navigate to it.
I also think some way of archiving pages would help, so that when one goes to a section, it's easy to tell what's current. For example, I went here today
https://puredata.info/docs/developer, and honestly, it I felt like it was going to take longer to sort out what is up to date than it would to just find the information elsewhere. :-/
I am literally dealing with this exact thing at my money work, so it's not like it's a phenomenon reserved for open source. Systems where anyone can write and contribute without any kind of central oversight really have a way of becoming a quagmire of outdated or miscategorized content because it's easy to write more, but folks are reluctant (understandably) to prune other people's content. Not sure what the answer is, but it seems like that's the case to me.
my two cents canadian!