Isn't the same true for matrix as well?

I appreciate xmpp as well but I have actually seen uses of matrix in open source community etc. a lot more so what are your thoughts on it?

Note for anyone interested in matrix, to not use the main matrix.org but other instances as well to actually have more decentralization/distribution

Yes, you're right, matrix too. However, I've tried ruining servers for both, synapse for matrix and prosody for xmpp and I should say matrix felt very sluggish and limited, while prosody is fast and insanely flexible. In addition, client software for XMPP is more diverse and feature-rich, I'm particularly impressed by movim (web) and conversations (android). Also, there are variety of bridges for everything, e.g. matrix <-> whatsapp or xmpp <-> telegram, so one is not limited too much while committing to a certain messaging tech.

Unless you are going to self-host, you would be required to provide government ID for registration on a server.