I love deferring to World Anvil for my campaigns. I love using the Plots as the skeleton of the session while the Notebook is for making things personalized for my groups. The complication is that, my notebook then gets clogged with outdated content I've gained over the years. Trying to sift through it slowly becomes more overwhelming.
I think doing things like with the campaigns and worlds where you can toggle active and storage can help clean up space a bit more. That way, the current content can be seen immediately while storage doesn't.
For me, I like to archive old prep notes to see how far I've come and to see how the world I use has been evolving overtime especially.
Just wished for this myself. I have done a complete reboot of my setting and campaigns, and while I would like to save previous notes, I wish I could close them out and only have them visible if I go looking for them.
Organizational features are always nice! I too need a way to keep my old notes from clogging up my notebook.