Go ahead, go outside onto the streets, and proclaim "I want lots of people murdered. The more we murder, the better. We really should get started now, what are you waiting for" and see where that's going to end, even in places like the US. Then realise that showing the Nazi salute expresses that exact same thing.
There's no such thing as non-criminal fascism. Thus advocating for it is advocating for, condoning, approving etc. of crimes which is a crime literally everywhere, rightfully so.
I think activity spread out quite a bit. During the exodus everyone was posting into the same two and a half meme communities causing massive churn on the front page and giant threads, but now everyone has created and/or settled into their comfortable little corners so any particular portion of lemmy looks less active, while overall it's larger.