The assumption is that centrally managed social media is bad because their algorithm is bad. But actually, they are bad because they are centrally managed and force one algorithm onto you. I’m not even advocating algorithm-by-choice. Even instance-specific algorithms would already work and would make the whole experience much more enjoyable and less boring. And if an instance’s algorithm(s) is too aggressive, it gets defederated. That would result in a much more exciting experience imo. And by the way: what’s the problem with getting old posts back in the timeline if it makes the overall conversation more interesting?
Lemmy uses simple filters. It has no memory of what you have looked at and takes nothing into consideration other than the chosen filter at the moment. You can even link directly to the filter because it is part of the url.
https://lemmy.world/?dataType=Post&listingType=All&page=1&sort=Hot
This is searching for the entire federated space of lemmy.world and sorting by hot. You might argue that “hot” is an algorithm, but it is also only determined by things such as creation date, upvotes and comments. Everyone gets exactly the same view so it isn’t specially curated.