Moxie openly admits he centralized because it is easier and that decentralizing is too hard. We should all just give up and pick the least bad centralized service.
With that thinking we would all be using AOL.
Making a robust flexible protocol that can support a bunch of different client and service implementations is hard, but that is how we ended up avoiding email and web browsing being controlled by a single entity.
Matrix is solving the hard problem of providing the core functionality of tools like Slack and Whatsapp without sacrificing user freedom or asking you to trust any one entity.
This is what ethical engineering looks like, and I don't mind tolerating occasional growing pains in exchange for freedom.