Second, the whole point of AI NLP search (i.e., 2nd part = loss) is that it does not need metadata (which was the basis of the now mostly abandoned semantic web approach to KM).
If you don't include the right metadata, google won't rank you highly. If you include the right metadata, your content will get higher rankings and the snazzy preview cards on different social media platforms.
Metadata is good! There are structural incentives to be mediocre though.
Yes, there's a very good reason not to use metadata: it's extra work, and it's not very fun, just like writing docs for software. So people don't want to do it because it isn't "sexy" (and there aren't very good incentives to overcome people's reluctance to do that work).
Because of this, just like any job that people don't really want to do, you have to "bully and cajole" them into doing it.
1) Link to the documentation in your tools
2) Ensure everyone has edit access to the linked documents
Another idea might be, whenever a new feature is closed out, auto-allocate some percentage of its implementation time to documentation, and schedule an interview with a tech writer.
So, to solve the first staleness part, there is only two ways: raise the documenter status, or make it possible (easier?) for someone else to do it. are they both really that hopeless?
PS: to solve the second loss/discovery part, I think we are heading for that AI powered simple "unified search" experience.