I took a quick look and it seems that SDF is not defederated from virtually ANYTHING at all (just one instance that as it was dying got taken over by spam) - not even the known CSAM (Child Sexual Abuse Material) ones, nor the most controversial triad across the entire Threadiverse: lemmygrad.ml, hexbear.net, and the one that the main Lemmy software developers also run, lemmy.ml.

One time I said something in hexbear.net along the lines that Biden, who was then President, at least lowered gas prices, so at least there was that - and my inbox just BLEW UP with replies streaming in for WEEKS and WEEKS afterwards. Then I did something similar at lemmygrad.ml with the same result. They are purely engagement trolls, enjoying their argumentation style of... well, as you said it. They are basically 4chan.

And it is not like I am on a campaign to wipe out their very existence, but neither do I want to recommend the Threadiverse/Fediverse to people if that is the kind of experience that those people will receive - and then look weirdly at me for having recommended it to them in the first place. There are stories aplenty on r/RedditAlternatives saying exactly as you: they came, they got disgusted with what they saw, and they immediately noped out, heading right back to Reddit. People here can be kind - whereas on Reddit that is extremely rare, especially in the larger subs. Traffic here is low and you can feel like you will be heard - on Reddit you are buried beneath an avalanche of thousands of comments, some of which are proven bots (repeating identical patterns of messages spaced years apart, just from different account names but they are word-for-word and it is beyond any rational thought of credulity to think that they could be otherwise - e.g. if you repeated this, my entire message here back to me, not even just this sentence or paragraph but the entire thing, then I would surmise that you had copied and pasted it, not responded organically, and would not believe you if you claimed otherwise, especially upon finding out that you literally could get paid irl money $$$ for having done so, to increase "engagement stats" and therefore advertising revenue).

I doubt you will remain long on SDF - the Lemmy software has very few features to help you deal with such trolling, although you can help reduce the clutter a little bit by blocking the instance. Unfortunately this does not "block" the "instance", instead only muting the communities on it - leaving the users there free to reply to you in other communities, triggering notifications, blowing up your inbox, and otherwise wasting your time. You will convert nobody there as they exist in their own artificial echo chamber realities, and instead you will become more like them.

I recommend checking out PieFed - the list of features that it has that Lemmy lacks is long and it is FANTASTIC! e.g. polls, flairs (both user and post), Topics/Feeds that are both user-customizeable and shareable, etc. etc. etc. etc. etc., but most importantly the ability to block all users from an instance, which that one feature alone silences I am not even kidding basically 99% of all trolling negative experiences on the entire platform. See more at https://join.piefed.social/ e.g. a list of instances at https://join.piefed.social/try/. Or if you want to stay with Lemmy (but... why though?) and are in the USA then discuss.online or if in Europe then feddit.org - neither of which defederate from lemmy.ml nor allow you to personally do so unlike PieFed, but both of which at least defederate from both hexbear.net and lemmygrad.ml.

Unless you are also a troll:-P, but the above is still sound advice imho.