To be honest, I’m not a big fan of Twitter-like services (I find there’s way too much noise in such feeds), so I never really explored the Fediverse surrounding activitypub too much. Any criticism I have on Lemmy current structure is likely to extend to other parts of the Fediverse where similar approaches apply. So I guess you could see my points as rants on that approach for public cross-publishing in general, rather than Lemmy in particular. I guess I picked the target I feel the most interest towards and that I think has the most potential to become something I could use a lot.

If Mastodon (and the activitypub fediverse in general) has the same approach of cross-publishing and forces instances to serve the content from third parties, I think it’s risky that they don’t have a stronger policy towards whitelisting that imposes a tight control over what instances are allowed to have their content served through them, imho it’s asking for trouble to appear. So I think whitelisting was a justified approach in case of lemmy.

In my mind, the issue with whitelisting/blocklisting is the limitation on the reach of the federation. People would have to create multiple accounts to access networks that don’t federate, rather than using one account that can access it all. It makes sense for an internet forum to ban users, block them. But it would make no sense for an internet forum to explicitly block their (legit) users from visiting other forums.

So, ideally, it would be best to find a solution that allows users to access any instance that’s technically compliant with the protocol without having to impose the burden on each instance host to carry responsibility for the content of other instances.