You answered the question yourself.

Most Matrix users use the matrix.org Synapse installation. If the people running matrix.org decided to stop working with other homeservers, the result would be much the same as what happened when Google and Facebook became less friendly to other XMPP servers and stopped interoperating with them. This is not an issue with Ring.

Matrix is slightly different to XMPP in this respect, as rooms are shared over all participating servers. So if the matrix.org homeserver went down (as it ocassionally does), all the users on other servers continue without impact. As such, it's more like email than XMPP.

Meanwhile we're also working on supporting decentralised accounts in Matrix, so users can pick which set of servers they can use as a homeserver. This then gives the best of both worlds: a simple thinclient protocol that anyone can implement, and knowledge of precisely which servers and devices host your data.

Basically, Ring and Matrix have totally different architectures, and which you use probably depends on what you are optimising for :)

Respectfully, I disagree slight...while yes most users using matrix DO USE the matrix.org instance, if it does go down, there's nothing stopping users from hosting their own ABCXYZ.org home server - in fact the matrix.org team encourage that. So, there isn't the hard dependency on the matrix.org instance that you might believe.

There would be nothing stopping users from hosting their own homeserver, but there would be something preventing them from communicating with all the users still on matrix.org. And all the users still on matrix.org would stay there because the matrix.org homeserver would provide more value to them, by having more users, than a homeserver that can't communicate with most Matrix users.

Yeah, i see your point...I guess once a popular hub like the matrix.org home server goes "offline", the curve to "re-discover" your colleagues on their own NEW home servers - assuming they even set themselves up on their own self hosted home servers - is a pretty steep curve. Though some users already use their own home servers (like owning their own domain name to use for their email address), plenty of people siomply leverage an account strictly on matrix.org...so yeah, lots of people would "go offline" from the matrix protocol. (I begrudgingly see your point :-)