Moved to forum feedback. The is not non-technical topic as you pointed out.
Personally, I would just redirect all 404:s with 301 to archived forum for a while. The solution suggested by @moson seems a good one:
Why are articles disappearing? - #15 by moson
However, unfortunately the people with access to the server itself have better things to do. I’m not saying that this unimportant. But there are even more important matters, and we can’t postpone the actual distro maintenance indefinitely to fix forum issues.
That is unfortunate, and should be avoided if possible. However, it is the end of the world. Becoming popular is not a very high priority for Manjaro. We just want to make a good os.