Algorithms can be useful - and at a certain scale they’re necessary. Just look at Lemmy - even as small as it is there’s already some utility in algorithms like “Active”, “Hot” and “Scaled”, and as the number of communities and instances grows they’ll be even more useful. The trouble starts when there are perverse incentives to drive users toward one type of content or another, which I think is one of the fediverse’s key strengths.
Algorithm is just a fancy word for rules to sort by. “New” is an algorithm that says “sort by the timestamp of the submissions”. That one is pretty innocuous, I think. Likewise “Active” which just says “sort by the last time someone commented” (or whatever). “Hot” and “Scaled”, though, involve business logic – rules that don’t have one technically correct solution, but involve decisions and preferences made by people to accomplish a certain aim. Again in Lemmy’s case I don’t think either the “Hot” or “Scaled” algorithms should be too controversial – and if they are, you can review the source code, make comments or a PR for changes, or stand up your own Lemmy instance that does it the way you want to. For walled-garden SM sites like TikTok, Facebook and Twitter/X, though, we don’t know what the logic behind the algorithm says. We can speculate that it’s optimized to keep people using the service for longer, or encouraging them to come back more frequently, but for all intents and purposes those algorithms are black boxes and we have to assume that they’re working only for the benefits of the companies, and not the users.