Ah that's a bummer really. I am just kinda skeptical of centralized services. Relying on the benevolence of a single party for your communication is risky.
E: This probably goes for all the chat services which are even mildly popular (WhatsApp, Telegram, Signal, Threema etc.). Matrix seems to be an exception.
Signal’s founder Moxie Marlinspike is famously anti-federation. His argument is that communication will break down as some clients implement some features, while other clients don't. Your client has no guarantees that the client on the other end will understand what it sends. Moxie points to the chaotic state of XMPP clients and servers as an example of this. So, he calls for a single client connecting to a single server where everyone agrees on what functionality is present.
Yeah this is my main beef with Signal. I don't want to end up in yet another walled garden. I see much more benefit to the open standard approach that made the internet great. Matrix is where it's at for me.
To me, it's a sound argument and he's convinced me. Fighting the status quo by constantly improving in a short amount of time is incompatible with decentralisation. It's the same reason e-mail hasn't been able to change and improve, or encrypted email still isn't practical, but I'll leave the meat of the argument to that video.
E: This probably goes for all the chat services which are even mildly popular (WhatsApp, Telegram, Signal, Threema etc.). Matrix seems to be an exception.