I wouldn't mind Reddit if it weren't for the opaque and hidden moderation. Tree nested communication is much more superior than traditional thread based communication. We need that in truly federated fashion, and lemmy was just a step there whose questionable leadership hampers any real wide-scale adoption.
Lemmy does slightly better, but essentially proves that when you have shitty administrators and moderators, the only thing that's going to be transparent is the quickest and easiest excuse, and when it's a lie it remains it remains incontestable. You only need to look at threads titled "Lemmy.ml tankie censorship problem" and read the comments to get a sense of the scale of the problem. Discord, at least it's much more obvious that you are joining closed off communities and that discussions are essentially time limited.
Things like community wikis have also dropped off in use specially recently because it's becoming clear how much of their content is intent on milking their users. First it was ads, and it was excused because "hosting costs" (regardless of how comparable they were), now it's AI scavenging your content and those services actively preventing you from eliminating content you contributed but are no longer willing to let them host.
Even in Lemmy, where's the option for me to remove my comments when I no longer want them to be hosted? In Lemmy, due to its federated nature, it's even more difficult, but given that you can edit comments and have those updates propagated, not impossible. But nothing beats reddit in abuse, where they shamelessly tried to say they would allow respect and allow users to monetize their content but instead proceeded to do the complete opposite. And now, the fact that there might/will be some other cache on the Internet that stores the content does not excuse it and give people the right to dismiss chain of ownership of those contributions.
Add to this that the economy is far worse and that the tech boom is shrinking and much more competition driven along with a general decline in society for respectful contributions and discourse, and you get a lot less of the sort of charity that was involved in older communities.