Reddit sells its api for high and is about to go for an IPO, its economy bases entirely on the data made by the users/communities. It is the work of the public, get robbed by a small group of individuals. A living example of capitalism.
Fediverse isn't enough to secure the publicity and usage of public data. What if the host of Lemmy instance also releases the snapshots of all the posts and modlogs, everyday, in the form of bittorrent? Only by doing so, we are safe from the host erasing public knowledge and data brokers.
Can't you already pull the data of an entire instance via the api?
You could ask the host through the api to do that, and that's the same the problem with Reddit. What we have changed here on Lemmy is more instances to choose from, the public knowledge grows with the instance and I wouldn't expect the host to let you access the data for free as the value(communities) grows.
There is real value in the data, way more than ever, bc it is the source for LLM.
So you fear that instance admins would start closing their apis. It would've been real helpful if that was on the on the original post.
The api is accessible and I don't see that changing because it is, y'know, required for federation. If you want backups, you can start scraping or host a private instance that subscribes to everything you want to save.
Releasing dumps the way you described would be a massive burden on admins, or even completely infeasible.
Think of the problem being solved. The Fediverse solves multiple problems, but most notably ensuring that our contributions won't be paywalled by some corporate grifter. The post and comment data itself is free and open, subject only to TOS and regional legislation.
If you consider your conversations valuable, stick with something like secure messaging application groups. And then hope nobody in that group does what you imagine in your second point.