Earlier, after review, we blocked and removed several communities that were providing assistance to access copyrighted/pirated material, which is currently not allowed per Rule #1 of our Code of Conduct.
The communities that were removed due to this decision were:
We took this action to protect lemmy.world, lemmy.world's users, and lemmy.world staff as the material posted in those communities could be problematic for us, because of potential legal issues around copyrighted material and services that provide access to or assistance in obtaining it.
This decision is about liability and does not mean we are otherwise hostile to any of these communities or their users. As the Lemmyverse grows and instances get big, precautions may happen. We will keep monitoring the situation closely, and if in the future we deem it safe, we would gladly reallow these communities.
The discussions that have happened in various threads on Lemmy make it very clear that removing the communites before we announced our intent to remove them is not the level of transparency the community expects, and that as stewards of this community we need to be extremely transparent before we do this again in the future as well as make sure that we get feedback around what the planned changes are, because lemmy.world is yours as much as it is ours.
The risk, however, is that you're going to be potentially liable for things that you DON'T see but are hosting due to federation.
Federation only duplicates stuff an instance's users subscribe to, so if you're a single user instance it wouldn't copy anything you don't see (if you actually vet your subscriptions and regularly view their content).
That was my thought as well. A single user instance with no local communities would only be storing posts from communities that one user subscribes to. Assuming the person subscribes to only what they want to see, that will be all they get (and any risks that come from storing information from those communities).
In a hypothetical situation where there are only single-user instances and community instances (instances that function as the source of communities), the only ones taking on risk would be the individual users subscribed to a community and owners of the instance hosting the community. There wouldn't be a need for an admin to make decisions to protect themselves that affect other users.
Those parentheses are doing a lot of heavy lifting.