@adam @patricia But while this works for you, it may not work for others. You have one set of needs, wishes, workflows, what have you - others have very different ones.

I'm OCD enough that I'd also love to have everything in one place, and matrix is certainly something to look at. But I wouldn't dream of forcing that upon my mother-in-law or colleagues or whoever else is asking my advice.

Building a safe DM mechanism - which at the very least solves the problem @patricia so elegantly laid out - should not be a difficult or controversial thing. If it is, then it is clear that the whole foundation is broken and failing to take actual people needs into account.

Anyone who's spent years learning how to avoid (to the extent possible) harrassment, stalking, bullying and outright abuse online will want to know that whichever measures they've put in place on platform A can be replicated on platform B without having to start from zero.
I have never been subjected to any of the above so my understanding of the pains involved is extremely superficial, at best. But I have no problem seeing they're very, very real.

Being idealistic in ones approach to this - while tempting and Star Trek-like in appearance - fails to recognise that humans of all kinds are involved; good and bad. There is no contradiction between advocating and creating open, distributed and federated platforms on the one side, and protecting individuals on the other.