Earlier quoted context omitted.
Moxie Marlinspike recently published an interesting essay that adressed this question. ”XMPP is an example of a federated protocol that advertises itself as a ’living standard.’ Despite its capacity for protocol ’extensions,’ however, it's undeniable that XMPP still largely resembles a synchronous protocol with limited support for rich media, which can't realistically be deployed on mobile devices. If XMPP is so exte…
I am hoping the Matrix team will write a blog post about their viewpoint on Moxie's post, given that they are out to do something Moxie doesn't believe can succeed. I'm also curious to hear how they respond to the specific section you quoted: how is Matrix going to avoid the same fate XMPP suffered here?
A quick specific answer w.r.t. XMPP is that Matrix aims for a very coarser granularity of modularity, published as a single consistent spec, and mandates feature profiles to determine which modules should get used where. In other words, there is only one official set of endpoints specified for Matrix for a given use case (e.g. mobile IM+VoIP). So it ends up being under tighter control (whilst still very much taking proposals and PRs from the overall community), and is easier to swap out the higher level layers to rapidly evolve functionality - rather than suffering the proliferation of XEPs which is XMPP's double-edged sword.
This is always going to move slower than a centralised service, but we think the freedom of being able to select your clients/servers/services is well worth that cost in agility - and does not have to compromise privacy if engineered correctly.