I don't doubt it. Threads I thought was more of a preemptive measure though, since iirc Meta wasn't ready to actually start sending any of its data towards the Fediverse. The "third" member of the big 3 then is lemmygrad.ml. Though most instances defederate from it, even if they don't defederate from hexbear.net or lemmy.ml, so possibly even without having defederated from it explicitly you aren't really seeing much content coming your way from it?
Oh no, your defederation is somehow wonky. I don't see lemmygrad.ml communities, not that I wanted to you understand but it's not in your defed list so they should be there, but I do see communities from both lemmy.ml and hexbear.net. Maybe simply adding the instance names is not enough and you need to "reinitialize" the data or some such? Here's one: https://quokk.au/c/memes@lemmy.ml and here's another: https://quokk.au/c/memes@hexbear.net. But then again... all the posts are old, so maybe that's how it is supposed to look? I dunno, so my message is probably confusing, but I thought I would offer it anyway just in case you didn't know, and if that helps you figure anything out!:-)
Yeah, that does help - e.g. if people started defederating lemmy.ml, then all the Hexbear users that went there after being defederated from many popular instances would make alts on other platforms and it would be much harder to avoid their continual trolling:-).
And yes I've previously had several quite pleasant conversations with people from lemmy.ml, though I have now managed to leave them behind by moving to PieFed.social where I can block the entire instance. I will block many innocent users that way but... I am okay with that, compared to the alternative of having to put up with each new one that comes along and harasses people. Many people of conscience are fleeing that instance anyway, and the rest have most definitely been warned so it's their choice, but I am not letting their recalcitrance dictate my own choices in turn:-).