I think it is a mistake to think of Lemmy as "Lemmy" in singular. Lemmy is just one of the software options that can be used to run independent websites that can optionally interact with each other via the ActvityPub protocol. The "All" feed is quite literally all that people on the same website have subscribed to, which is not a bad thing at all if you chose an instance with like minded people. Just think of it as crowdsourcing the discovery of interesting communities.

[–] wolfyvegan@slrpnk.net 2 points 2 days ago

This is precisely what I mean. You and I know that, but the average user might not, and so they would be less likely to discover similar/interesting communities on other instances, especially if they have their account on a relatively small instance, and would not even know to look for them elsewhere. Your explanation here, exactly as you've written it, would be helpful to people new to the Fediverse. If slrpnk.net won't use Lemmy Federate, then perhaps posting this explanation somewhere would let people know that "this is not all that there is" available to them.