You know, I've been on the Internet 20+ years and have been to some shady corners of it... but nowhere seems to have such a CSAM problem as Matrix and its friends apparently do. Why would that be?
I've seen it on the fediverse. Thanks to fediverse servers copying images to a local cache the moment something gets posted, hundreds or even thousands of servers started mirroring child porn because one dickhead liked to see the world burn.
My guess is that the source of the problem is that you can easily sign up for a service if it doesn't validate your phone number like every other messenger with a decent following does. If XMPP gained popularity again outside of corporate networks that use it without knowing, we'd also see it there, probably.
Matrix also seems to have gathered a following in the particularly unsavoury parts of a few *chan websites which probably doesn't help.
> My guess is that the source of the problem is that you can easily sign up for a service if it doesn't validate your phone number like every other messenger with a decent following does.
This is still relatively new and it's not as ubiquitous as say email verification. So I don't see that as being a primary cause of whatever the underlying issue is. Not to mention, I have to imagine it's never been easier to acquire phone numbers to abuse.
