I agree that the bickering is tedious and old at this point (and perhaps has been since the start), but there is a sense that the technical arguments miss the point of what the contention is about. Now, my argument is based mostly on conjecture and observation, and I mainly use XMPP because Conversations is the only thing that runs on my Blackberry Q10 (another thread entirely); I have not much of a horse in the race in any other way.
Though XMPP and Matrix are diametrically opposed in terms of their protocol semantics, and can be meant to occupy different use-cases at their edges (say, message passing vs. eventually-consistent data stores), their core use-cases are much the same: one-to-one and many-to-many messaging for both public and private groups, in competition with other, proprietary applications occupying the same space (e.g. Slack, Signal, Telegram, Discord). For sure, it might be agreed that there's a wide spectrum of difference even in the aforementioned proprietary applications (the whole banquets and barbecues notion), but I'm hoping it's not controversial to think that one can implement an application in the same UX vein as the proprietary alternatives using either XMPP and Matrix.
That, I feel, the the core of the contention -- that somehow Matrix has wrested focus/effort/velocity away from a still-viable project in terms of end-user-goals, thus somehow dooming it (or open-source/community-owned messaging in general) in the process. At face value, this might very well be nonsense; if XMPP cannot compete, or is not viable, nothing anyone outside the project does will affect this fact. Conversely, if Matrix didn't exist in its current form, it might not exist at all -- it's not a foregone conclusion that efforts would've been poured into XMPP or whatever else instead. In any case, competition is generally thought to be a good thing, insofar as it helps drive competitors to improve.
Emotionally, though, I think I understand the contention, and I've seen it happen not with protocols, but with things like Linux distributions, where people would lament the proliferation of disjoint efforts, where no clear, viable contender to the proprietary solutions existed at the time -- and some might argue does not exist still; nevertheless there's not much lamenting nowadays, where multiple viable distributions and desktop environments exist.
In some sense, community-owned messaging is still in a precarious state, and splitting up efforts, as it were -- since efforts are not just split in protocol implementation, but also in the ecosystem of applications etc. -- makes it feel even more precarious. Whether there's any rational basis to this, and whether either protocol has a technical advantage over the other, I don't know.
This isn't necessarily an endorsement of one protocol/ecosystem over the other, nor do I have direct experience with integrating Matrix or XMPP (though I run the latter on my home-server for family), but XMPP has seen a few large deployments, including in healthcare (in the UK)[0][1] and in Germany[2].
The consumer-facing client ecosystem for XMPP has indeed seen less rapid development than Matrix (the latter probably benefits from a more cohesive approach), but the server ecosystem for XMPP is very mature, and servers such as Ejabberd are known to scale to hundreds of thousands of connections on a single, modest host[3]. Obviously, that's only one part of the puzzle, hence why Matrix was chosen here.
Still, it'd be interesting to see how the two evolve and compare down the line.
Though XMPP and Matrix are diametrically opposed in terms of their protocol semantics, and can be meant to occupy different use-cases at their edges (say, message passing vs. eventually-consistent data stores), their core use-cases are much the same: one-to-one and many-to-many messaging for both public and private groups, in competition with other, proprietary applications occupying the same space (e.g. Slack, Signal, Telegram, Discord). For sure, it might be agreed that there's a wide spectrum of difference even in the aforementioned proprietary applications (the whole banquets and barbecues notion), but I'm hoping it's not controversial to think that one can implement an application in the same UX vein as the proprietary alternatives using either XMPP and Matrix.
That, I feel, the the core of the contention -- that somehow Matrix has wrested focus/effort/velocity away from a still-viable project in terms of end-user-goals, thus somehow dooming it (or open-source/community-owned messaging in general) in the process. At face value, this might very well be nonsense; if XMPP cannot compete, or is not viable, nothing anyone outside the project does will affect this fact. Conversely, if Matrix didn't exist in its current form, it might not exist at all -- it's not a foregone conclusion that efforts would've been poured into XMPP or whatever else instead. In any case, competition is generally thought to be a good thing, insofar as it helps drive competitors to improve.
Emotionally, though, I think I understand the contention, and I've seen it happen not with protocols, but with things like Linux distributions, where people would lament the proliferation of disjoint efforts, where no clear, viable contender to the proprietary solutions existed at the time -- and some might argue does not exist still; nevertheless there's not much lamenting nowadays, where multiple viable distributions and desktop environments exist.
In some sense, community-owned messaging is still in a precarious state, and splitting up efforts, as it were -- since efforts are not just split in protocol implementation, but also in the ecosystem of applications etc. -- makes it feel even more precarious. Whether there's any rational basis to this, and whether either protocol has a technical advantage over the other, I don't know.