Lemmy has a well-known reputation as being a "Nazi bar". e.g. as mentioned in this example post in r/RedditAlternatives complaining about toxicity on Lemmy, here is one of the comments therein (not from OP but as part of the overall conversation):
If their experience is anything like mine, it’s populated by mostly far left wing Americans who were banned from Reddit for being too extreme. I disagreed with someone about a topical left wing American position and received death threats. In fact I’ve never received that many death threats on Reddit. Lemmy is extreme.
Even if the threats came from Hexbear or one of the lemmy.ml mods who are allowed to make death threats against users without any repercussions, "we" still expose "our" users to such content when we federate with those communities. i.e., for exactly the same reason that we defederate from instances that share CSAM, if we really, truly, genuinely don't like it when mods make death threats against users, then we need to put a stop to it - by defederating those instances that are known to do exactly that.
Otherwise we give our tacit approval, and moreover whenever we encourage people to join Lemmy instances, we willingly expose those people to this kind of content. Would you expose someone to CSAM, knowingly and without warning them first? Then why is it different when we can see the death threats, delivered by mods, who are not censured in any way, yet still encourage people to come here to Lemmy communities? Are we truly that desperate for content that we are so inconsiderate to them as to expose them to that without warning?
If you somehow have not heard of this yet and really don't know what I'm talking about, a lot of details are offered in Discuss.Online's (successful) Petition to defederate from hexbear.net, although that particular mod in question is from Lemmy.ml.
Draces@lemmy.world 3 weeks ago
I had pretty much the same experience as that user and it’s why I left lemm.ee when they decided not to defederate with some of the worst instances. Was about to go back to the search if lemmy.world wasn’t any better. Tankies are why I don’t recommend Lemmy to my friends anymore. They are the fediverse’s biggest problem
OpenStars@piefed.social 3 weeks ago
I am currently at 100% of the people that I've told about Lemmy irl actively chiding me for having mentioned it to them. It doesn't help that (1) Lemmy.ml is the #1 Lemmy instance in a Google search, and (2) that instance uses Local rather than All when you don't have an account. If someone told me to consider joining Lemmy.ml, and that first couple of pages of content were all that I saw - especially just before any election in a Western nation - well then now I understand their reaction perfectly, as it is the correct one!?!?
Conversely, PieFed has a number of features that Lemmy lacks, one being the ability to actually block all users from an instance (rather than merely mute communities but not actual users on it - leaving them free to troll you in other communities, reply to your comments, trigger notifications, downvote your content, etc.). Since blocking lemmy.ml, I have had zero regrets, and enjoy interacting with Lemmy communities much better:-).
The real biggest problem that Lemmy has is lack of users and overall dearth of niche content - which ofc wraps back around to why would someone willing come here to be bullied just for being a mainstream centrist or even "leftist" by USA standards (Reddit is based in and its largest userbase is from the USA)?
Bullying is why Lemmy will never grow. That, and how the tools are somehow even more authoritian than Reddit - i.e. there is a modlog but no modmail, nor notification of a moderation event, instead the modlog simply says that a "mod" did something, if you go to the trouble to find out why nobody bothered to respond. And worse, on Lemmy.ml you'll find yourself banned from communities that you've never so much as heard of, citing having broken a rule that seems not written down anywhere. The lack of transparency is very reminiscent of the spez.
Fortunately, PieFed and Mbin offer non-Lemmy options to the Threadiverse.:-)