Here's what I would love from Mastodon/Fediverse: by default, posts are deleted after a reasonably short period of time, say 3 weeks.
I see this is a ephemeral conversation mechanism, not a storage mechanism. I don't dig through history and the interface doesn't seem to encourage that either. If you miss something, so be it. And if you want to preserve everything, well, I'm sure there would be the option.