There is still only one implementation of the Matrix homeserver protocol. Just one.
But hey, at least we have built-in VOIP and color unicode emojiis. You couldn't possibly have a successor to IRC without features like those. Glad the Matrix folks have their priorities straight.
No, you couldn't if you want to ever reach any reasonable threshold of adoption. Most people don't care in the slightest, if they even know about, for federation. They want emojis, and being able to video call grandson. I'd argue stories has been turning into a requirement as well. The WhatsApp feature set.
Then you have a lot of people who want the Discord feature set. Any missing feature and "this sucks let's go to Discord".
The world has already tried decentralization without putting the average user's needs and wants first, it's called XMPP and it's there for you to use and call the echo server, if there even is one to respond. Matrix has a long way to go, but at least it hasn't given up before it started.
Saying XMPP "gave up before it started" is nonsense. There is plenty of usage and development activity across a bunch of projects. Check out the monthly newsletter for some highlights: https://xmpp.org/newsletter/
Our project https://snikket.org/ is using XMPP and has all the features you listed. My 85yo grandmother does in fact use it to video call her grandson, regularly :)
I don't use XMPP since the Google talk era, how are the available servers nowadays? Does they support federation, meaning that users from different servers can talk to each other?
I use it on and off to participate in a few small communities. It can sometimes be frustrating to find a server with the right setup for the clients I like to use, but when I finally do, I have no problems. I have only seen one non-federated server.
I can't speak for the backend, because I've never hosted a server myself, but I find the good XMPP clients to have many more features and to be much more performant than the good Matrix ones.
Your facts are wrong; there are hundreds of dendrite (go) and conduit (rust) Matrix instances live on the network these days, as well as instances of the original synapse Python implementation. Admittedly dendrite and conduit are beta, but then so was synapse until 2020.
There is still only one implementation of the Matrix homeserver protocol. Just one.
But hey, at least we have built-in VOIP and color unicode emojiis. You couldn't possibly have a successor to IRC without features like those. Glad the Matrix folks have their priorities straight.